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To assess the long-term (20-year) endocrine therapy benefit in premenopausal patients with breast cancer.Secondary analysis of the Stockholm trial (STO-5, 1990-1997) randomly assigning 924 premenopausal patients to 2 years of goserelin (3.6 mg subcutaneously once every 28 days), tamoxifen (40 mg orally once daily), combined goserelin and tamoxifen, or no adjuvant endocrine therapy (control) is performed. Random assignment was stratified by lymph node status; lymph node-positive patients (n = 459) were allocated to standard chemotherapy (cyclophosphamide, methotrexate, and fluorouracil). Primary tumor immunohistochemistry (n = 731) and gene expression profiling (n = 586) were conducted in 2020. The 70-gene signature identified genomic low-risk and high-risk patients. Kaplan-Meier analysis, multivariable Cox proportional hazard regression, and multivariable time-varying flexible parametric modeling assessed the long-term distant recurrence-free interval (DRFI). Swedish high-quality registries allowed a complete follow-up of 20 years.In estrogen receptor-positive patients (n = 584, median age 47 years), goserelin, tamoxifen, and the combination significantly improved long-term distant recurrence-free interval compared with control (multivariable hazard ratio [HR], 0.49; 95% CI, 0.32 to 0.75, HR, 0.57; 95% CI, 0.38 to 0.87, and HR, 0.63; 95% CI, 0.42 to 0.94, respectively). Significant goserelin-tamoxifen interaction was observed (This study shows 20-year benefit from 2 years of adjuvant endocrine therapy in estrogen receptor-positive premenopausal patients and suggests differential treatment benefit on the basis of tumor genomic characteristics. Combined goserelin and tamoxifen therapy showed no benefit over single treatment. Long-term follow-up to assess treatment benefit is critical.

Background: Women with estrogen receptor (ER)-positive disease have a long-term risk of distant recurrence. The poor survival of premenopausal women diagnosed with breast cancer combined with the otherwise long life expectancy makes it especially important to identify tumor characteristics associated with long-term survival. Intra-tumor heterogeneity, having cancer cells of varying characteristics across the tumor, may promote therapeutic resistance and metastatic capacity. We have previously shown that high intra-tumor heterogeneity of ER increases the risk of fatal breast cancer. To our knowledge, the relation between intra-tumor heterogeneity of progesterone receptor (PR) expression and long-term survival is not known. We aimed to study the association between intra-tumor heterogeneity of PR and long-term survival of premenopausal women in the Stockholm tamoxifen trial (STO-5), with 20-years complete follow-up. Methods: This study was a secondary analysis of 504 ER-positive/PR-positive premenopausal women from the STO-5 trial (1990-1997). 451 women had human epidermal growth factor receptor 2 (HER2)-negative tumors. Patients were randomized to receive either 2 years of endocrine treatment (tamoxifen and/or goserelin) or no endocrine treatment. Lymph node-positive patients (n=251) also received standard chemotherapy (CMF). Immunohistochemical analysis, including estimating the proportion of tumor cells for each PR intensity level (0, 1+, 2+, or 3+), was completed in 2020. Intra-tumor heterogeneity of PR was calculated using Rao’s quadratic entropy and then categorized into low and high intra-tumor heterogeneity groups, using a predefined cutoff at the second tertile. Complete long-term (20 year) follow-up was obtained from high-quality Swedish registries. Long-term distant recurrence-free interval (DRFI) was assessed using univariate Kaplan-Meier analysis and multivariable Cox proportional hazard modeling, adjusting for patient and tumor characteristics. Results: A statistically significant difference in 20-year DRFI was seen between patients with high and low intra-tumor heterogeneity of PR in the univariate Kaplan-Meier analysis (log-rank P< 0.01). Survival proportions for DRFI at 20 years were 60.2% (95% CI, 53.2%-68.1%) and 73.3% (95% CI, 68.6%-78.3%) for patients with high and low PR intra-tumor heterogeneity, respectively. Analysis in patients with HER2-negative tumors yielded similar results. In the multivariable analysis, women with high intra-tumor heterogeneity of PR had a significantly increased long-term risk of distant recurrence, compared to women with low intra-tumor heterogeneity, hazard ratio (HR)=1.49 (95% CI, 1.08-2.06). The same pattern was seen in HER2-negative women, HR=1.50 (95% CI, 1.06-2.12), see Table. Conclusions: This study suggests an increased long-term risk of distant recurrences in ER-positive/PR-positive premenopausal women with high intra-tumor heterogeneity of PR as compared to women with low intra-tumor heterogeneity of PR, independent of HER2 status. Ongoing analyses include using deep learning for image analysis of breast cancer tumors to examine intra-tumor heterogeneity at higher resolution and for various tumor characteristics. Better understanding of tumor characteristics associated with long-term risk in premenopausal women is needed, given the poor prognosis and early onset of the disease. Long-term risk of distant recurrence by PR intra-tumor heterogeneity and HER2 status Multivariable Cox proportional hazard regression modeling of 20-year distant recurrence-free interval (DRFI) by high and low PR intra-tumor heterogeneity. ER-positive/PR-positive and ER-positive/PR-positive/HER2-negative premenopausal women were analyzed separately. The crude model was adjusted for age, randomization year, lymph node status, and endocrine treatment. The full model was adjusted for age, randomization year, lymph node status, endocrine treatment, tumor size, Ki-67 status, and HER2 status. Citation Format: Oscar Danielsson, Huma Dar, Gizeh Perez-Tenorio, Anna Nordenskjöld, Christina Yau, Christopher C. Benz, Laura J. Esserman, Bo Nordenskjöld, Olle Stål, Tommy Fornander, Annelie Johansson, Linda S. Lindström. Long-term survival and intra-tumor heterogeneity of progesterone receptor expression in estrogen receptor-positive/progesterone receptor-positive premenopausal women with breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-03.

Background: Tamoxifen is an established treatment for breast cancer, but its long-term effects on survival and on secondary cancers are not fully evaluated. Material and methods: We studied 30 years outcome of 4124 postmenopausal patients who were randomized to receive (totally) two or five years of adjuvant tamoxifen. Results: After 5 years of follow-up, when tamoxifen treatment was finished in both groups, until 15 years of follow-up, overall mortality (HR 0.80, 95% CI 0.72 – 0.90, p< 0.001), breast cancer mortality for all patients (HR 0.80, 95% CI 0.68 – 0.94, p= 0.006) and breast cancer mortality for patients with estrogen receptor positive disease (HR 0.67, 95% CI 0.55 – 0.83, p< 0.001) were significantly reduced in the five-year group as compared to the two-year group. After 15 years, the difference remained but did not further increase. In the five-year group, the incidence of contralateral breast cancer was gradually reduced during the entire period of observation. The incidence of lung cancer was also reduced in the five-year group. In contrast there was an increased endometrial cancer incidence in the five-year group and for those receiving 40 mg of tamoxifen this incidence was further increased. Conclusion: Three more years of tamoxifen therapy reduced the risk of breast cancer mortality. The difference was established during the first 15 years after randomization. Moreover, the incidence of contralateral breast cancer gradually decreased for 30 years. The incidence of lung cancer was reduced in the five-year group. In contrast the incidence of endometrial cancer was increased.

Purpose: In vitro, p21-activated kinase 1 (Pak1) phosphorylates the serine 305 residue of the estrogen receptor α (ERα) and influences the response of breast cancer cells to tamoxifen. We investigated the influence of Pak1 and pERαser305 on breast cancer prognosis and results of tamoxifen therapy.Experimental Design: We examined Pak1 and pERαser305 protein by immunohistochemistry in a series of 912 tumors from node-negative breast cancer patients randomized to tamoxifen or no adjuvant endocrine treatment.Results: Cytoplasmic Pak1 correlated to large tumors and ER negativity, whereas nuclear Pak1 and pERαser305 correlated to small tumors and ER positivity. Nuclear expression of Pak1 and pERαser305 predicted reduced response to tamoxifen in patients with ERα-positive tumors (tamoxifen versus no tamoxifen: hazard ratio (HR), 1.33; 95% confidence interval (95% CI), 0.42-4.2; P = 0.63), whereas patients lacking this combination benefitted significantly from tamoxifen (HR, 0.43; 95% CI, 0.30-0.62; P < 0.0001). Similar nonsignificant trends were detected in analyses of the proteins separately. Pak1 in the cytoplasm was an independent prognostic marker, indicating increased recurrence rate (HR, 1.79; 95% CI, 1.17-2.74; P = 0.0068) and breast cancer mortality (HR, 1.98; 95% CI, 1.14-3.46; P = 0.016) for patients randomized to no adjuvant treatment.Conclusion: Our results suggest that patients with tumors expressing Pak1 and pERαser305 in combination are a group in which tamoxifen treatment is insufficient. In addition, the pathway may be of interest as a drug target in breast cancer. Furthermore, the findings support previous studies showing that Pak1 has differential roles in the cytoplasm and the nucleus. Clin Cancer Res; 16(5); 1624–33

Supplementary Figures 1-7 - PDF file 117K, Supplementary Figure 1. Cohorts used for BCI model training and validation Supplementary Figure 2. Performance of H:I and MGI for early (0-5 years) and late (> 5 years) distant recurrence in Stockholm ER+, LN- untreated patients. A, C: H:I, 0-5 years and > 5 years. B, D: MGI, 0-5 years and > 5 years. Supplementary Figure 3. BCI risk groups for prediction of overall distant recurrence in Stockholm TAM and Multi-institutional cohorts, ER+, LN- patients. Supplementary Figure 4. Continuous BCI score for overall (0 - 10 years) rate of distant recurrence in Stockholm TAM cohort. Supplementary Figure 5. BCI risk groups for prediction of early and late distant recurrence in the combined StockholmTAM and Multi-institutional cohort; ER+, LN-, tamoxifen-treated patients. Supplementary Figure 6. Continuous BCI score for early (0 - 5 years) and late (> 5 years) rate of distant recurrence in the combined Stockholm TAM and Multi-institutional cohort (ER+, LN-, tamoxifen-treated patients). Supplementary Figure 7. Prediction of tamoxifen benefit by H/I. A: no benefit of tamoxifen in H/I-low patients. B: benefit of tamoxifen in H/I-high patients

Supplementary Data from Estrogen Receptor-α Phosphorylation at Serine 305, Nuclear p21-Activated Kinase 1 Expression, and Response to Tamoxifen in Postmenopausal Breast Cancer

Supplementary Tables 1-2 - PDF file 101K, Supplementary Table 1. Kaplan-Meier estimates of overall distant recurrence free survival (DRFS) for 3 BCI risk groups in Stockholm TAM-treated and Multi-institutional cohorts. Supplementary Table 2. Overall distant recurrence: Univariate and multivariate Cox model analysis after stepwise variable selection by AIC of likelihood of overall distant recurrence in Stockholm TAM and Multi-institutional cohorts for all ER+ and ER+, HER2- patients

ERRα protein expression and clinicopathological variables with respect to estrogen receptor (ER) and HER2 status.

Supplementary figure 1: Validation of the ERRα antibody used for immunohistochemical analysis; Supplementary Figure 2: The prognostic value of ERRα protein expression and subcellular location in adjuvant-untreated ER-negative patients; Supplementary Figure 3: ERRα protein expression is not prognostic in ER-positive breast cancer.

Purpose: Residual risk of relapse remains a substantial concern for patients with hormone receptor–positive breast cancer, with approximately half of all disease recurrences occurring after five years of adjuvant antiestrogen therapy.Experimental Design: The objective of this study was to examine the prognostic performance of an optimized model of Breast Cancer Index (BCI), an algorithmic gene expression–based signature, for prediction of early (0–5 years) and late (>5 years) risk of distant recurrence in patients with estrogen receptor–positive (ER+), lymph node–negative (LN−) tumors. The BCI model was validated by retrospective analyses of tumor samples from tamoxifen-treated patients from a randomized prospective trial (Stockholm TAM, n = 317) and a multi-institutional cohort (n = 358).Results: Within the Stockholm TAM cohort, BCI risk groups stratified the majority (∼65%) of patients as low risk with less than 3% distant recurrence rate for 0 to 5 years and 5 to 10 years. In the multi-institutional cohort, which had larger tumors, 55% of patients were classified as BCI low risk with less than 5% distant recurrence rate for 0 to 5 years and 5 to 10 years. For both cohorts, continuous BCI was the most significant prognostic factor beyond standard clinicopathologic factors for 0 to 5 years and more than five years.Conclusions: The prognostic sustainability of BCI to assess early- and late-distant recurrence risk at diagnosis has clinical use for decisions of chemotherapy at diagnosis and for decisions for extended adjuvant endocrine therapy beyond five years. Clin Cancer Res; 19(15); 4196–205. ©2013 AACR.

Purpose: Estrogen-related receptor alpha (ERRα) signaling has recently been implicated in breast cancer. We investigated the clinical value of ERRα in randomized cohorts of tamoxifen-treated and adjuvant-untreated patients.Experimental Design: Cox proportional hazards regression was used to evaluate the significance of associations between ERRα gene expression levels and patient DMFS in a previously published microarray dataset representing 2,000 breast tumor cases derived from multiple medical centers worldwide. The 912 tumors used for immunostaining were from a tamoxifen-randomized primary breast cancer trial conducted in Stockholm, Sweden, during 1976–1990. Mouse model was used to study the effect of tamoxifen treatment on lung colonization of MDA-MB-231 control cells and MDA-MB-231 cells with stable knockdown of ERRα. The phenotypic effects associated with ERRα modulation were studied using immunoblotting analyses and wound-healing assay.Results: We found that in ER-negative and triple-negative breast cancer (TNBC) adjuvant-untreated patients, ERRα expression indicated worse prognosis and correlated with poor outcome predictors. However, in tamoxifen-treated patients, an improved outcome was observed with high ERRα gene and protein expression. Reduced ERRα expression was oncogenic in the presence of tamoxifen, measured by in vitro proliferation and migration assays and in vivo metastasis studies.Conclusions: Taken together, these data show that ERRα expression predicts response to tamoxifen treatment, and ERRα could be a biomarker of tamoxifen sensitivity and a prognostic factor in TNBC. Clin Cancer Res; 22(6); 1421–31. ©2015 AACR.

Background: Tamoxifen is a standard endocrine therapy for both pre- and postmenopausal ER-positive breast cancer patients. Patients with ER-positive disease have a long-term risk of distant recurrence, thus, long-term follow-up studies are essential to understand true treatment benefit. Clinically used tumor characteristics are prognostic 5-10 years after primary diagnosis, however, whether these characteristics are predictive of long-term tamoxifen benefit is largely unexplored. Therefore, we aimed to determine the long-term tamoxifen therapy benefit by the clinically used tumor characteristics in pre- vs postmenopausal patients in the Stockholm tamoxifen (STO)-trials with 20-years complete follow-up. Methods: Secondary analysis of 1242 ER-positive/HER2-negative patients from the STO-trials, randomized to at least 2 years of 40 mg tamoxifen vs no endocrine therapy (control). Premenopausal lymph node-positive patients were allocated to chemotherapy as standard of care and postmenopausal high-risk patients were further randomized to chemotherapy vs radiotherapy. Tumor immunohistochemical analysis was recently conducted. Complete 20-year follow-up was obtained from Swedish high-quality registries. Long-term distant recurrence-free interval (DRFI) was assessed by multivariable Cox proportional hazard regression and time-varying analysis using flexible parametric modelling. Results: Premenopausal patients showed significantly improved long-term DRFI from tamoxifen vs control if they were lymph node-negative (Hazard Ratio [HR]=0.46; 95% CI, 0.24-0.87), PR-positive (HR=0.61; 95% CI, 0.41-0.91), or of genomic low risk (HR=0.47; 95% CI, 0.26-0.85), see Table. In postmenopausal patients, significantly improved long-term DRFI from tamoxifen vs control was seen for all good prognosis tumor characteristics, i.e. small tumor size (pT≤20mm: HR=0.55; 95% CI, 0.39-0.77), tumor grade 1-2 (HR=0.55; 95% CI, 0.41-0.73), lymph node-negative (HR=0.44; 95% CI, 0.30-0.64), PR-positive (HR=0.60; 95% CI, 0.44-0.80), Ki-67-low (< 15%: HR=0.51; 95% CI, 0.38-0.68), and genomic low risk (HR=0.53; 95% CI, 0.37-0.74), see Table. Also, postmenopausal patients with large tumor size (pT>20mm: HR=0.64; 95% CI, 0.44-0.94) and PR-negative tumors (HR=0.51; 95% CI, 0.32-0.81) showed significant long-term tamoxifen benefit. Time-varying analysis in premenopausal patients indicated that tamoxifen therapy benefit diminished over time. Significant tamoxifen benefit until year 5, 10, and 15 after primary diagnosis was observed for PR-positive, lymph node-negative, and genomic low-risk patients, respectively. Postmenopausal patients had a significant long-term tamoxifen benefit if they had tumors of small or large tumor size, tumor grade 1-2, lymph node-negative status, PR-positive status, low Ki-67 levels, or genomic low risk. Conclusions: This study suggests a differential long-term tamoxifen therapy benefit in pre- vs postmenopausal patients. Clinically defined low-risk postmenopausal patients have long-term tamoxifen benefit, whereas the benefit is absent or diminish over time for premenopausal patients. Improved long-term prognostic and endocrine therapy predictive markers in premenopausal breast cancer patients with poor prognosis and long life-expectancy is needed, which could involve molecular tools. Long-term tamoxifen benefit in premenopausal and postmenopausal breast cancer patients by the clinically used tumor characteristics. Table Multivariable Cox proportional hazard regression analysis of 20-year distant recurrence-free interval (DRFI) for patients with ER-positive/HER2-negative tumors, comparing patients randomized to tamoxifen vs patients randomized to no endocrine therapy (control). Adjusted for age, randomization year, tumor size, tumor grade, lymph node status, PR status, Ki-67 status, chemotherapy, radiotherapy, and type of surgery. Citation Format: Annelie Johansson, Huma Dar, Anna Nordenskjöld, Gizeh Perez-Tenorio, Christina Yau, Christopher C. Benz, Laura J. Esserman, Laura Van’t Veer, Bo Nordenskjöld, Olle Stål, Tommy Fornander, Linda S. Lindström. Differential Long-Term Benefit from Adjuvant Tamoxifen Therapy in Estrogen Receptor (ER)-Positive/Human Epidermal Growth Factor Receptor 2 (HER2)-Negative Premenopausal and Postmenopausal Breast Cancer Patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-03-11.

Background: The risk for patients with estrogen receptor (ER)-positive breast cancer remains stable decades after primary diagnosis, with a large proportion of distant metastatic events occurring late. Thus, long-term follow-up studies are essential to understand true treatment benefit. Tamoxifen (TAM) therapy is a fundamental endocrine treatment for ER-positive breast cancer. We have previously shown a long-term tamoxifen therapy benefit for patients with less aggressive tumor characteristics in ER-positive/HER2-negative patients. However, ER-positive breast cancer is highly heterogenous and can be separated into different molecular subpopulations that behave differently during extended follow-up. The long-term tamoxifen benefit by molecular subtype is largely unexplored. We therefore aimed to investigate the long-term benefit from tamoxifen by clinically used tumor characteristics in Luminal A vs Luminal B patients in the Stockholm tamoxifen (STO)-trials with complete 20-years follow-up. Methods: Secondary analysis of ER-positive/HER2-negative patients with Luminal A or B molecular subtype (n=952) from the STO-trials (1976-1997) randomized to TAM (40 mg) vs no endocrine therapy (control). Gene expression data was generated using custom designed Agilent arrays from FFPE breast cancer tumor tissue and was used to define PAM50 molecular subtypes. The clinically used markers were reannotated in 2014 and 2020. Complete 20-year follow-up was obtained from Swedish high-qualitative registries. The long-term distant recurrence-free interval (DRFI) was assessed by Kaplan-Meier, multivariable Cox proportional hazard regression and time-varying analysis, using flexible parametric modelling. Results: Multivariable analysis showed significantly improved long-term DRFI from TAM vs control for both Luminal A (HR=0.59; 95% CI, 0.44-0.81) and Luminal B (HR=0.67; 95% CI, 0.46-0.99) patients. Time-varying analysis showed that patients with Luminal A subtype significantly benefitted from TAM for 15 years (HR=0.60, 95% CI, 0.39-0.94 at year 15), whereas patients with Luminal B subtype had a significant TAM benefit for 5 years (HR=0.64, 95% CI, 0.42-0.98 at year 5), see Table. Furthermore, a significant long-term TAM benefit for patients with large tumor size (pT>20mm: HR=0.46; 95% CI, 0.25-0.84), tumor grade 1-2 (HR=0.55; 95% CI, 0.40-0.77), lymph node-negative (HR=0.51, 95% CI, 0.34-0.78), PR-positive (HR=0.57, 95% CI, 0.40-0.81) and Ki-67-low tumors (HR=0.55, 95% CI, 0.39-0.77) was seen for Luminal A patients. In Luminal B patients, significantly improved long-term DRFI from TAM vs control was seen for small tumor size (pT≤20mm: HR=0.44; 95% CI, 0.24-0.80), tumor grade 1-2 (HR=0.51; 95% CI, 0.29-0.90), lymph node-negative (HR=0.40, 95% CI, 0.19-0.83), PR-positive (HR=0.59, 95% CI, 0.38-0.93) and Ki-67-low tumors (HR=0.45, 95% CI, 0.25-0.84). Conclusions: This study suggests a 15 years tamoxifen benefit for patients with Luminal A subtype tumors, whereas the benefit for patients with Luminal B tumors is up to five years after diagnosis. Furthermore, our study suggests a long-term tamoxifen benefit for patients with less aggressive tumor characteristics regardless of tumor subtype, except for tumor size in Luminal A patients. ER-positive breast cancer is a heterogeneous disease and long-term follow-up studies in molecular subtypes are essential to understand differences in treatment benefit. Table. Time-varying analysis of long-term tamoxifen therapy benefit by PAM50 molecular subtype. Time-varying analysis of distant recurrence-free interval (DRFI) to assess how tamoxifen benefit varied over the 20 year of follow-up using flexible parametric survival modelling. Patients included in analyses with no missing values. Estimated hazard ratios (HR) at year 5, 10, 15 and 20 for patients with Luminal A or Luminal B molecular subtype tumors randomized to tamoxifen therapy, as compared with patients randomized to no endocrine therapy (control). Adjusted for age, period of primary breast cancer diagnosis, tumor size, tumor grade, lymph node status, PR status, Ki-67 status, chemotherapy, radiotherapy, type of surgery, and menopausal status. *indicates significant findings P Citation Format: Huma Dar, Annelie Johansson, Anna Nordenskjöld, Gizeh Perez-Tenorio, Christina Yau, Christopher C. Benz, Laura J. Esserman, Bo Nordenskjöld, Olle Stål, Tommy Fornander, Linda S. Lindström. Long-Term Benefit from Adjuvant Tamoxifen in Luminal A and Luminal B Breast Cancer Patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-03-04.

The clinical impact of tumor-infiltrating lymphocytes (TILs) is less known for breast cancer patients with the estrogen receptor-positive (ER+)/human epidermal growth factor receptor-negative (HER-) subtype. Here, we explored the prognostic and predictive value of TILs regarding distant recurrence-free interval (DRFI) and breast cancer-specific survival (BCSS) in 763 postmenopausal patients randomized to receive tamoxifen vs. no systemic treatment. TILs were assessed in whole section tumor samples stained with HE and divided into low (lt;10%), intermediate (10-39%), or high (≥40%). High TILs were associated with poor prognostic variables and good prognoses for all patients, but not within the ER+/HER2- group. Within the ER+/HER2- group, high gene expression of CD19 and PD-L1 and high IMMUNE1 score indicated good prognosis in multivariable analysis while high CD8 and CD19 gene expression and high IMMUNE1 score were associated with less tamoxifen benefit. These results indicate that within the ER+/HER2- subtype there could be subsets of patients where expression of specific TIL markers might be used to reveal candidates for immune therapy interventions upon failure of the endocrine therapy.

The metastatic potential of estrogen receptor (ER)-positive breast cancers is heterogeneous and distant recurrences occur months to decades after primary diagnosis. We have previously shown that patients with tumors classified as ultralow risk by the 70-gene signature have a minimal long-term risk of fatal breast cancer. Here, we evaluate the previously unexplored underlying clinical and molecular characteristics of ultralow risk tumors in 538 ER-positive patients from the Stockholm tamoxifen randomized trial (STO-3). Out of the 98 ultralow risk tumors, 89% were luminal A molecular subtype, whereas 26% of luminal A tumors were of ultralow risk. Compared to other ER-positive tumors, ultralow risk tumors were significantly (Fishers test, P < .05) more likely to be of smaller tumor size, lower grade, progesterone receptor (PR)-positive, human epidermal growth factor 2 (HER2)-negative and have low Ki-67 levels (proliferation-marker). Moreover, ultralow risk tumors showed significantly lower expression scores of multi-gene modules associated with the AKT/mTOR-pathway, proliferation (AURKA), HER2/ERBB2-signaling, IGF1-pathway, PTEN-loss and immune response (IMMUNE1 and IMMUNE2) and higher expression scores of the PIK3CA-mutation-associated module. Furthermore, 706 genes were significantly (FDR < 0.001) differentially expressed in ultralow risk tumors, including lower expression of genes involved in immune response, PI3K/Akt/mTOR-pathway, histones, cell cycle, DNA repair, apoptosis and higher expression of genes coding for epithelial-to-mesenchymal transition and homeobox proteins, among others. In conclusion, ultralow risk tumors, associated with minimal long-term risk of fatal disease, differ from other ER-positive tumors, including luminal A molecular subtype tumors. Identification of these characteristics is important to improve our prediction of nonfatal vs fatal breast cancer. Funding Agencies|Swedish Research Council (Vetenskapsradet)Swedish Research Council [2020-02466]; Swedish Research Council for Health, Working life and Welfare (FORTE) [2019-00477]; Gosta Milton Donation Fund (Stiftelsen Gosta Miltons donationsfond); Swedish Cancer SocietySwedish Cancer Society [180385, 190140]; Stockholm Cancer Society (Cancerforeningen i Stockholm); California Breast Cancer Research Program (CBCRP) [180B-0065]; National Institutes of Health (NIH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [U01-CA196406]

The PIK3CA gene, encoding the p110α catalytic subunit of PI 3-kinase (PI3K), is mutated in more than 30% of breast cancers. Most mutations concentrate to the hotspots E542K and E545K and H1047R and are associated with hyperactivation of the phosphatidylinositol 3′-kinase/Akt pathway in vitro. The estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) (ER+/HER2-) breast cancers stand for more than 40% of the PIK3CA mutations where these constitute a new therapeutic target for endocrine-treatment resistant advanced breast cancers. Although PIK3CA is an oncogene, its mutations are associated with good prognosis. Here, we explored the prognostic and predictive role of PIK3CA hotspot mutations for low-risk postmenopausal breast cancer patients randomized to receive tamoxifen vs. no systemic treatment, followed for over 25 years and with extensive clinical records. Mutation analysis was performed using formalin-fixed paraffin-embedded tumors with digital droplet PCR (ddPCR). PIK3CA mutations were present in 35,6% of patients, predominantly within the ER+/HER2- subtype (49,8%) compared with the HER2+ and TNBC subtypes. The most frequent mutation found in all patients was H1047R (18%) followed by E545K (14%) and E542K (6%). Significant associations were found between all hotspot mutations and low grade, positive progesterone receptor (PR) expression, HER2 negative status, low Ki-67 (proliferation marker), and high expression score of a PIK3CA-mutation-associated gene module. Moreover, PIK3CA mutations were often found in patients with ultralow risk to develop distant recurrences according to the 70-gene signature. All PIK3CA mutations were coupled with longer distant recurrence-free interval (DRFI) in all patients in univariate and multivariable analysis after adjusting for tumor size, receptor status (ER, PR, HER2), tumor grade, Ki-67 and tamoxifen: HR multivariable (95% CI)=0.53 (0.28-0.98). In agreement with our previous results, PIK3CA mutations indicated good prognosis for patients with highly proliferative tumors (Ki-67>15%): H.R multivariable (95% CI)=0.15 (0.03-0.69) and high risk by the 70-gene signature: HR multivariable (95% CI)=0.14 (0.03-0.61) but not for low proliferative tumors (Ki-67 Citation Format: Carolin Jönsson, Zeinab Alkashaf, Josefine Sandström, Annelie Johansson, Tommy Fornander, Linda S. Lindström, Gizeh Perez Tenorio. PIK3CA hotspot mutations as biomarkers for prognosis and treatment prediction in low-risk postmenopausal breast cancer patients [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B027.

Clinically used breast cancer markers, such as tumor size, tumor grade, progesterone receptor (PR) status, and Ki-67 status, are known to be associated with short-term survival, but the association of these markers with long-term (25-year) survival is unclear.To assess the association of clinically used breast cancer markers with long-term survival and treatment benefit among postmenopausal women with lymph node-negative, estrogen receptor [ER]-positive and ERBB2-negative breast cancer who received tamoxifen therapy.This study was a secondary analysis of data from a subset of 565 women with ER-positive/ERBB2-negative breast cancer who participated in the Stockholm tamoxifen (STO-3) randomized clinical trial. The STO-3 clinical trial was conducted from 1976 to 1990 and comprised 1780 postmenopausal women with lymph node-negative breast cancer who were randomized to receive adjuvant tamoxifen therapy or no endocrine therapy. Complete 25-year follow-up data through December 31, 2016, were obtained from Swedish national registers. Immunohistochemical markers were reannotated in 2014. Data were analyzed from April to December 2020.Patients in the original STO-3 clinical trial were randomized to receive 2 years of tamoxifen therapy vs no endocrine therapy. In 1983, patients who received tamoxifen therapy without cancer recurrence during the 2-year treatment and who consented to continued participation in the STO-3 study were further randomized to receive 3 additional years of tamoxifen therapy or no endocrine therapy.Distant recurrence-free interval (DRFI) by clinically used breast cancer markers was assessed using Kaplan-Meier and multivariable Cox proportional hazards analyses adjusted for age, period of primary diagnosis, tumor size (T1a and T1b [T1a/b], T1c, and T2), tumor grade (1-3), PR status (positive vs negative), Ki-67 status (low vs medium to high), and STO-3 clinical trial arm (tamoxifen treatment vs no adjuvant treatment). A recursive partitioning analysis was performed to evaluate which markers were able to best estimate long-term DRFI.The study population comprised 565 postmenopausal women (mean [SD] age, 62.0 [5.3] years) with lymph node-negative, ER-positive/ERBB2-negative breast cancer. A statistically significant difference in long-term DRFI was observed by tumor size (88% for T1a/b vs 76% for T1c vs 63% for T2 tumors; log-rank P .001) and tumor grade (81% for grade 1 vs 77% for grade 2 vs 65% for grade 3 tumors; log-rank P = .02) but not by PR status or Ki-67 status. Patients with smaller tumors (hazard ratio [HR], 0.31 [95% CI, 0.17-0.55] for T1a/b tumors and 0.58 [95% CI, 0.38-0.88] for T1c tumors) and grade 1 tumors (HR, 0.48; 95% CI, 0.24-0.95) experienced a significant reduction in the long-term risk of distant recurrence compared with patients with larger (T2) tumors and grade 3 tumors, respectively. A significant tamoxifen treatment benefit was observed among patients with larger tumors (HR, 0.53 [95% CI, 0.32-0.89] for T1c tumors and 0.34 [95% CI, 0.16-0.73] for T2 tumors), lower tumor grades (HR, 0.24 [95% CI, 0.07-0.82] for grade 1 tumors and 0.50 [95% CI, 0.31-0.80] for grade 2 tumors), and PR-positive status (HR, 0.38; 95% CI, 0.24-0.62). The recursive partitioning analysis revealed that tumor size was the most important characteristic associated with long-term survival, followed by clinical trial arm among patients with larger tumors.This secondary analysis of data from the STO-3 clinical trial indicated that, among the selected subgroup of patients, tumor size followed by tumor grade were the markers most significantly associated with long-term survival. Furthermore, a significant long-term tamoxifen treatment benefit was observed among patients with larger tumors, lower tumor grades, and PR-positive tumors.

BackgroundBreast cancer tumors are heterogenous, including their metastatic potential and time to distant metastasis. Patients with estrogen receptor (ER)-positive tumors have a continuous long-term risk of fatal disease decades after diagnosis. Recently, ER-positive breast cancer patients classified as having ultralow risk tumors by the 70-gene expression signature (MammaPrint) were associated with a minimal risk of fatal disease. However, the underlying tumor characteristics of ultralow risk tumors are unknown.MethodsSecondary analysis of the Stockholm tamoxifen randomized trial (STO-3, 1976-1990) enrolling postmenopausal lymph node-negative breast cancer patients. Immunohistochemistry of the clinically used breast cancer markers (n=727 patients) and gene expression profiling by Agilent microarrays (n=652 patients) were performed in 2014. Ultralow risk tumors, identified by the 70-gene signature, were compared to other ER-positive tumors (of low/high risk) and Luminal A and B PAM50 subtype tumors (ER-positive, low/high risk) by the clinical markers and multi-gene modules, representative of specific biological processes and pathways, using Fisher’s exact test. Furthermore, differential gene expression analysis was performed contrasting ultralow risk tumors to other ER-positive tumors (of low/high risk) using t-statistics and false discovery rate (FDR).ResultsUltralow risk tumors were significantly (P

Purpose The protein tyrosine phosphatase, non-receptor type 2 (PTNP2) regulates receptor tyrosine kinase signalling, preventing downstream activation of intracellular pathways like the PI3K/Akt pathway. The gene encoding the protein is located on chromosome 18p11; the 18p region is commonly deleted in breast cancer. In this study, we aimed to evaluate PTPN2 protein expression in a large breast cancer cohort, its possible associations to PTPN2 gene copy loss, Akt activation, and the potential use as a clinical marker in breast cancer. Methods PTPN2 protein expression was analysed by immunohistochemistry in 664 node-negative breast tumours from patients enrolled in a randomised tamoxifen trial. DNA was available for 146 patients, PTPN2 gene copy number was determined by real-time PCR. Results PTPN2 gene loss was detected in 17.8% of the tumours. Low PTPN2 protein expression was associated with higher levels of nuclear-activated Akt (pAkt-n). Low PTPN2 as well as the combination variable low PTPN2/high pAkt-n could be used as predictive markers of poor tamoxifen response. Conclusion PTPN2 negatively regulates Akt signalling and loss of PTPN2 protein along with increased pAkt-n is a new potential clinical marker of endocrine treatment efficacy, which may allow for further tailored patient therapies. Funding Agencies|Swedish Cancer Society; Cancer Research Foundations of Radiumhemmet; Cancer Society in Stockholm; King Gustav V Jubilee Clinical Research Foundation; ALF grants Region Ostergotland; Onkologiska Klinikernas i Linkoping Forskningsfond

Background: Tumor size and nodal status are prognostic for risk of both early and late disease recurrence in patients with early stage, HR+ breast cancer, and are incorporated into both adjuvant chemotherapy and extended endocrine therapy treatment decisions. In a recent EBCTCG meta-analysis of over 46,000 patients [Pan H, et al. J Clin Oncol 34, 2016 (suppl; abstr 505)], risk of late distant recurrence was assessed in patient subsets based on nodal status and tumor size. Patients with T1N0 disease who were treated with 5 years endocrine therapy had a good overall prognosis, with 4%, 9%, and 14% risk of distant recurrence from years 5-10, 5-15, and 5-20, respectively. Breast Cancer Index (BCI) has been validated as prognostic biomarker for risk of both early and late distant recurrence in multiple randomized trial cohorts. The aim of this analysis was to assess distant recurrence (DR) risk stratification with BCI in patients with clinically low-risk T1N0 tumors. Methods: Primary tumor samples from the subset of patients with T1N0 disease from 2 independent validation cohorts of HR+ breast cancer patients were examined [Stockholm randomized controlled trial (N=259) and a retrospective multi-institutional cohort (N=237)]. Patients in the Stockholm RCT cohort were treated with adjuvant tamoxifen only; patients in the multi-institutional cohort were treated with adjuvant tamoxifen +/- chemotherapy (20.3%). No patients received extended endocrine therapy. Kaplan-Meier analysis was used to assess the risk of DR within distinct BCI risk groups. Time dependent analysis was performed by combining BCI Low and Intermediate risk groups for risk of early recurrence (0-5y), and BCI Intermediate and High risk groups for risk of late recurrence (>5y). Results: In the Stockholm cohort, BCI identified 13% of T1N0 patients as high risk for relapse within the first 5y, and these patients had a significantly reduced distant recurrence-free survival (DRFS, 85.3%) compared to BCI Low Risk patients (97.7%; P=0.0004). In patients disease-free at year 5, BCI identified 32% of patients as high risk for late recurrence; these patients had significantly lower DRFS (86.7%) between years 5-15 compared to BCI low risk patients (95.4%; P=0.0263). In the multi-institutional cohort, 22% of T1N0 patients were identified by BCI as high risk for relapse within the first 5y, and these patients had a significantly reduced DRFS (77.3%) compared to BCI low risk patients (96.2%; P Conclusions: HR+ Patients with favorable clinical features (T1N0) have a good overall prognosis. However, results of this study demonstrated that adding molecular resolution on tumor biology with BCI identified a significant subset of women with higher risk of both early and late distant recurrence; findings support consideration of genomic classification in T1N0 patients to identify additional candidates for adjuvant chemotherapy and/or extended endocrine therapy, respectively. Citation Format: Schroeder BE, Zhang Y, Stal O, Fornander T, Brufsky A, Sgroi DC, Schnabel CA. Prognostic impact of genomic risk stratification with breast cancer index in patients with clinically low risk, hormone receptor-positive, node-negative, T1 breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-14.

Background We and others have shown that the clinically used breast cancer markers alter their expression throughout tumor progression, influencing patient survival (Lindström et al, JCO 2012). What are the likely explanations to our findings? Here, we aimed to determine whether breast cancer intra-tumor heterogeneity of the estrogen receptor (ER) is a marker of tumor aggressiveness and benefit of tamoxifen therapy in a large randomized trial. Material and methods The Stockholm Tamoxifen (STO-3) trial enrolled postmenopausal lymph node negative breast cancer patients with a tumor size of less than 30 mm, between 1976 and 1990, to be randomized to receive adjuvant tamoxifen versus not. From the original randomized trial cohort approximately half of the patients (778 patients) had primary tumor formalin-fixed paraffin-embedded blocks available and were included in our study. No significant differences in age and period of diagnosis, type of surgery received, receptor status, tumor grade and size were observed between the treatment arms. All tumor slides were immunostained in a central laboratory using the SP1 antibody. ER slides were scored by two independent breast cancer pathologists assessing the fraction of cancer cells for each ER intensity level (0, +1, +2 or +3) compared to established standards. The resulting distribution of ER stained tumor cells defines intra-tumor heterogeneity of ER (Rao's quadratic entropy (QE),Potts et al, Lab Invest 2012). Intra-tumor heterogeneity was categorized using the third tertile as cut-off for high heterogeneity (726 patients). Analyses of long-term breast cancer specific survival (25 years) by intra-tumor heterogeneity of ER were performed using univariate Kaplan-Meier and multivariate Cox proportional hazard modeling adjusting for treatment arm, age and period of diagnoses, ER, progesterone receptor (PR), HER2, Ki-67, tumor grade, and tumor size. Further, a test of correlation was performed to investigate whether intra-tumor heterogeneity of ER was correlated to the percentage of ER positive cells, the H-Score or the Luminal A and B subtype (PAM50). Results In the univariate Kaplan-Meier analyses, a statistically significant difference in long-term survival by intra-tumor heterogeneity of ER was seen for all patients (log rank, P=0.018), tamoxifen treated arm (log rank, P=0.0033), but not untreated arm (log rank, P=0.19). However in the multivariate analysis, patients with high intra-tumor heterogeneity of ER in the treated arm as well as in the untreated arm had an almost two-fold increased long-term risk of fatal breast cancer disease as compared to patients with low or intermediate heterogeneity (Treated arm: HR, 2.06; 95% CI, 1.04-4.07 and Untreated arm: HR, 1.71; 95% CI, 1.01-2.87). No significant correlation of intra-tumor heterogeneity to the tested variables was seen. Conclusions Patients with high intra-tumor heterogeneity of ER had less benefit from tamoxifen therapy and an increased long-term risk of fatal breast cancer disease. Our findings should be clinically relevant since therapy benefit was evaluated in a randomized trial with long-term follow-up. Citation Format: Lindström LS, Yau C, Czene K, Thompson CK, van't Veer LJ, Nordenskjöld B, Stål O, Fornander T, Benz CC, Borowsky AD, Esserman LJ. Intra-tumor heterogeneity of the estrogen receptor predicts less benefit from tamoxifen therapy and poor long-term breast cancer patient survival – Retrospective analyses of the STO-3 randomized trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-03.

Cancer-associated fibroblasts (CAFs) regulate tumour growth, metastasis and response to treatment. Recent studies indicate the existence of functionally distinct CAF subsets. Suggested mechanisms whereby CAFs can impact on treatment response include paracrine signalling affecting cancer cell drug sensitivity and effects on tumour drug uptake. PDGFRβ is an important regulator of fibroblasts. Experimental studies have linked PDGFRβ-positive fibroblasts to metastasis and also to reduced tumour drug uptake. This study has investigated the potential role of PDGFRβ-positive fibroblasts in response to adjuvant tamoxifen treatment of breast cancer. Analyses of two breast cancer collections from randomised studies analysing adjuvant tamoxifen treatment in early breast cancer demonstrated significant benefit of tamoxifen in the group with low stromal PDGFRβ, which was not observed in the group with high stromal PDGFRβ. In general terms these findings provide novel evidence, derived from analyses of randomised clinical studies, of response-predictive capacity of a marker-defined subset of CAFs and, more specifically, identify stromal PDGFRβ as a marker related to tamoxifen benefit in early breast cancer.

To study agreement between recommended adjuvant treatment after primary breast cancer (BC) surgery from the clinical based National Breast Cancer Register and initiated adjuvant treatment from medical records; factors associated with agreement; and reasons for discontinuation or change of planned treatment.Included were 970 women who had undergone BC surgery, aged 20-63 years, living in Stockholm County, and literate in Swedish.Distant metastases, pre-surgical chemotherapy, and/or a previous BC diagnosis. Information on clinical tumor stage, surgical treatment, recommended adjuvant radiotherapy, chemotherapy, and endocrine therapy was obtained from the BC register. Type of initiated adjuvant treatments, if treatment plan was followed, and reasons for discontinuation were extracted from medical records.The register had high completeness and agreement was high, 94-96%, (κ 0.801-0.908) for all types of treatment. Disagreement regarding radiotherapy and chemotherapy was associated with having ≥1 lymph node metastases and more extended axillary surgery, and for radiotherapy also more extended breast surgery. There were no such associations with age, tumor size, or invasiveness. None of these factors were associated with disagreement regarding recommended versus initiated endocrine therapy. Endocrine therapy was most often discontinued (24%), mostly due to toxicity which was also the most common reason for discontinuation of chemotherapy.Swedish register data on recommended treatment has high validity in women aged 24-63 years, with limited BC, and demonstrates utility as a proxy for initiated treatment in this group. This is of interest since extracting data from medical records is resource demanding.

Introduction:The expression of estrogen receptor (ER) and progesterone receptor (PgR) predicts the response to endocrine therapy of breast cancer. Nearly all PgR positive tumors are also ER positive. The independent predictive information of PgR has been questioned after an overview by the EBCTCG. However, the studies in the overview were performed before modern PgR immunohistochemistry (IHC) was developed. Purpose: We aim to investigate the independent predictive value of PgR determined by IHC in ER positive tumors. Materials and methods: Between 1976 and 1990 the Stockholm Breast Cancer Study Group conducted a randomized trial comparing adjuvant tamoxifen versus control. We evaluated 618 patients with ER-positive "low-risk" breast cancer ( tumor size≤ 30 mm and lymph node-negative) for whom PgR was determined by immunohistochemistry. The median follow-up was 17 years. Hazard ratios (HRs) and 95 % confidence intervals (CIs) were estimated using the Cox's proportional hazards model. Results: Patients with ER+/PgR+ tumors receiving tamoxifen had a reduced recurrence risk compared with those who were not treated with tamoxifen (HR= 0.40, 95% CI 0.27 – 0.59, p< 0.001). For patients with ER+/PgR- tumors the difference between tamoxifen vs. no tamoxifen treatment was not statistically significant (HR= 0.88, 95% CI 0.51 – 1.52, p= 0.65). P for interaction between the groups was 0.02. Tam vs. controlPgR (IHC)HR (95% CI)P valueP for interactionRecurrence-free survival≥ 10 %0.40 (0.27 - 0.59)< 0.0010.02 < 10 %0.88 (0.51 - 1.52)0.65 Distant recurrence-free survival≥ 10 %0.41 (0.25 - 0.65)< 0.0010.08 < 10 %0.80 (0.44 - 1.47)0.47 Breast-cancer specific survival≥ 10 %0.35 (0.21 - 0.60)< 0.0010.11 < 10 %0.70 (0.37 - 1.33)0.28 Conclusion: Our results indicate that the PgR expression adds predictive value to the ER expression regarding benefit from tamoxifen treatment. Citation Format: Fohlin H, Nordenskjöld A, Fornander T, Löfdahl B, Skoog L, Stål O. Progesterone receptor positivity is an independent predictor of long-term benefit from adjuvant tamoxifen treatment of estrogen receptor positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-19.

Background Better tools are needed to identify breast cancer patients at very low risk of dying from their disease. We applied a previously specified 'Ultralow risk' threshold for the FDA-cleared MammaPrint 70-gene expression score to predict long-term absence of breast cancer-specific mortality in a Swedish randomized trial of breast cancer patients treated with tamoxifen (Tam) versus not and followed for more than 25 years. Methods Between 1976-1990 the Stockholm Tamoxifen (STO) trial enrolled and randomized node negative breast cancer patients with tumor size less than 30 mm to receive 2 years of Tam versus not, without regard to hormone receptor status. In the Tam-treated arm, patients without relapse at 2 years were further randomized to receive 3 additional years of Tam versus no additional endocrine therapy. From the original STO randomized trial cohort, about half (778 cases) had remaining formalin-fixed paraffin-embedded primary tumor blocks for additional tumor characterization and MammaPrint analysis. In this validation dataset, which now has >25 years follow-up, breast cancer-specific survival was assessed between MammaPrint scored 'Ultralow risk', 'Low risk' or 'High risk' categories by Kaplan-Meier analyses and multivariate Cox proportional hazard modeling, adjusting for treatment, age, period of diagnosis, tumor size, grade, receptor (ER, PR, HER2) and Ki-67 status. Results: In this unscreened patient population MammaPrint scored 15% of patients as 'Ultra-low risk', 43% as 'Low risk' and 42% as 'High risk'. At 20 years, a statistically significant difference in survival between risk categories was seen for all patients (log rank, P=0.0001), the Tam treated arm (log rank, P=0.0088) and the untreated arm (log rank, P=0.014). Ultra-low risk patients have significantly lower risk of disease-specific death relative to Low and High risk patients in our multivariate Cox analysis. Among Ultra-low risk patients there were no deaths out to 15 years in the Tam-treated arm; by 20 years, disease-specific survival in Tam-treated and untreated arms were 94% and 90%. The majority of Tam-treated patients received only 2 years of treatment, with ∼35% going on to receive 5 years of treatment. All Ultra-low risk cases were HR+HER2-. 78% were luminal A by PAM50; but only 31% of luminal A were Ultra-low risk. Invasive ductal (no-special-type) carcinomas were the most frequent, but lobular, tubular, invasive papillary and invasive cribriform subtypes were enriched and mucinous types were absent. Conclusions: Node-negative, T15 y) metastatic recurrence risk exists if left untreated, 'Ultralow risk' status could identify women for whom lumpectomy alone and a short course of adjuvant endocrine therapy is sufficient. Given the high frequency (∼50%) of such 'Ultralow risk' tumors detected in modern screening cohorts (e.g. MINDACT), a substantial fraction of newly diagnosed women could benefit from more targeted and less aggressive local and adjuvant therapy. Citation Format: Esserman LJ, Thompson CK, Yau C, van 't Veer LJ, Borowsky AD, Tobin NP, Nordenskjöld B, Fornander T, Stål O, Benz CC, Lindström LS. Identification of tumors with an indolent disease course: MammaPrint ultralow signature validation in a retrospective analysis of a Swedish randomized tamoxifen trial. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-09-01.

Background: Hormone receptor expression is an indication for endocrine therapy, however, receptor status is insufficient to account for the considerable heterogeneity of response, and additional predictive biomarkers are needed. The HoxB13/IL17BR (H/I) gene expression ratio has previously been shown to be predictive of benefit from extended endocrine therapy for women with estrogen receptor-positive (ER+) breast cancer treated in the MA.17 trial. In this correlative study, H/I was compared with ER, PR, and HER2 expression in assessing response to adjuvant tamoxifen (TAM) versus untreated (UNT) in ER+, node-negative patients from the prospective, randomized Stockholm trial. Methods: Analysis included 600 ER+, LN- patients (317 TAM, 283 untreated) from the Stockholm cohort. Expression profiles were generated by RT-PCR for H/I, ER, PR, and HER2, with additional IHC studies for ER, PR, and HER2. Multivariate Cox models including age, tumor size and tumor grade, were used to assess the significance of the interaction between treatment and each biomarker as continuous variables. 10-year risk of distant recurrence, as a function of each continuous biomarker, was estimated from Cox model in each of the 2 treatment arms. Results: The interaction between H/I and TAM treatment was significant (p = 0.003). Consistent with the significant interaction, the 10-year rate of distant recurrence as a function of continuous H/I demonstrated that the reduction in recurrence rates with TAM correlated with increasing H/I. Interaction P values for all other biomarkers were nonsignificant [ER (PCR), P=0.473; ER (IHC), p=0.371; PR (PCR), p=0.555; PR (IHC), p=0.475; HER2 (PCR), p=0.947, and HER2 (IHC), p=0.839]. The treatment effect of tamoxifen was unchanged across ER, PR, and HER2 expression levels. Conclusions: Results of this study provide further support for HoxB13/IL17BR as a biomarker of endocrine response. The H/I gene expression ratio, but not ER, PR, or HER2 expression evaluated as continuous variables, was predictive of benefit from adjuvant TAM treatment. Findings indicate that H/I endocrine response activity is not strictly correlated with ER+ expression and provides independent predictive information regarding estrogen signaling-driven recurrences. Citation Format: Yi Zhang, Brock E Schroeder, Piiha-Lotta Jerevall Jannok, Tommy Fornander, Olle Stal, Catherine A Schnabel, Dennis C Sgroi. Prediction of benefit from endocrine therapy in ER+ early stage breast cancer: Correlative studies of the breast cancer index HoxB13/IL17BR (H/I) ratio, ER, PR, and HER2 expression in the randomized Stockholm trial [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-06-06.

Breast cancer molecular prognostic tools that predict recurrence risk have mainly been established on endocrine-treated patients and thus are not optimal for the evaluation of benefit from endocrine therapy. The Stockholm tamoxifen (STO-3) trial which randomized postmenopausal node-negative patients to 2-year tamoxifen (followed by an optional randomization for an additional 3-year tamoxifen vs nil), versus no adjuvant treatment, provides a unique opportunity to evaluate long-term 20-year benefit of endocrine therapy within prognostic risk classes of the 70-gene prognosis signature that was developed on adjuvantly untreated patients. We assessed by Kaplan-Meier analysis 20-year breast cancer-specific survival (BCSS) and 10-year distant metastasis-free survival (DMFS) for 538 estrogen receptor (ER)-positive, STO-3 trial patients with retrospectively ascertained 70-gene prognosis classification. Multivariable analysis of long-term (20 years) BCSS by STO-3 trial arm in the 70-gene high-risk and low-risk subgroups was performed using Cox proportional hazard modeling adjusting for classical patient and tumor characteristics. Tamoxifen-treated, 70-gene low- and high-risk patients had 20-year BCSS of 90 and 83%, as compared to 80 and 65% for untreated patients, respectively (log-rank p amp;lt; 0.0001). Notably, there is equivalent tamoxifen benefit in both high (HR 0.42 (0.21-0.86), p = 0.018) and low (HR 0.46 (0.25-0.85), p = 0.013) 70-gene risk categories even after adjusting for clinico-pathological factors for BCSS. Limited tamoxifen exposure as given in the STO-3 trial provides persistent benefit for 10-15 years after diagnosis in a time-varying analysis. 10-year DMFS was 93 and 85% for low- and high-risk tamoxifen-treated, versus 83 and 70% for low- and high-risk untreated patients, respectively (log-rank p amp;lt; 0.0001). Patients with ER-positive breast cancer, regardless of high or low 70-gene risk classification, receive significant survival benefit lasting over 10 years from adjuvant tamoxifen therapy, even when given for a relatively short duration. Funding Agencies|California Breast Cancer Research Program BCRP award [180B-0065]; Breast Cancer Research Foundation [BCRF]; Swedish Research Council [521-2014-2057]; FORTE [2014-1962]; Stiftelsen Gosta Miltons Donationsfond [The Gosta Milton Donation Fund]; Cancerforeningen i Stockholm [Stockholm Cancer Society]

Patients with estrogen receptor (ER)-positive breast cancer have a long-term risk for fatal disease. However, the tumor biological factors that influence the long-term risk and the benefit associated with endocrine therapy are not well understood.To compare the long-term survival from tamoxifen therapy for patients with luminal A or luminal B tumor subtype.Secondary analysis of patients from the Stockholm Tamoxifen (STO-3) trial conducted from 1976 to 1990, which randomized postmenopausal patients with lymph node-negative breast cancer to receive adjuvant tamoxifen or no endocrine therapy. Tumor tissue sections were assessed in 2014 using immunohistochemistry and Agilent microarrays. Only patients with luminal A or B subtype tumors were evaluated. Complete long-term follow-up data up to the end of the STO-3 trial on December 31, 2012, were obtained from the Swedish National registers. Data analysis for the secondary analysis was conducted in 2017 and 2018.Patients were randomized to receive at least 2 years of tamoxifen therapy or no endocrine therapy; patients without recurrence who reconsented were further randomized to 3 additional years of tamoxifen therapy or no endocrine therapy.Distant recurrence-free interval (DRFI) by luminal A and luminal B subtype and trial arm was assessed by Kaplan-Meier analyses and time-dependent flexible parametric models to estimate time-varying hazard ratios (HRs) that were adjusted for patient and tumor characteristics.In the STO-3 treated trial arm, 183 patients had luminal A tumors and 64 patients had luminal B tumors. In the untreated arm, 153 patients had luminal A tumors and 62 had luminal B tumors. Age at diagnosis ranged from 45 to 73 years. A statistically significant difference in DRFI by trial arm was observed (log rank, P .001 [luminal A subtype, n = 336], P = .04 [luminal B subtype, n = 126]): the 25-year DRFI for luminal A vs luminal B subtypes was 87% (95% CI, 82%-93%) vs 67% (95% CI, 56%-82%) for treated patients, and 70% (95% CI, 62%-79%) vs 54% (95% CI, 42%-70%) for untreated patients, respectively. Patients with luminal A tumors significantly benefited from tamoxifen therapy for 15 years after diagnosis (HR, 0.57; 95% CI, 0.35-0.94), and those with luminal B tumors benefited from tamoxifen therapy for 5 years (HR, 0.38; 95% CI, 0.24-0.59).Patients with luminal A subtype tumors had a long-term risk of distant metastatic disease, which was reduced by tamoxifen treatment, whereas patients with luminal B tumors had an early risk of distant metastatic disease, and tamoxifen benefit attenuated over time.

Background: G protein-coupled estrogen receptor (GPER), also known as GPR30, is a novel putative estrogen receptor. Although contradictory results have been presented e.g. regarding the subcellular localization and function of the receptor, previous studies have shown a prognostic value in breast cancer and proposed treatment predictive information for tamoxifen (Tam). This study aimed at clarifying the prognostic and treatment predictive value for Tam of GPER, in different subcellular localizations, by using samples from a randomized clinical trial - the ideal population for assessing treatment prediction. Material and Methods: GPER levels were assessed semi-quantitatively by immunohistochemistry in tissue microarrays from 742 postmenopausal breast cancer patients with no lymph node metastasis and tumor size ≤ 30mm. Patients were originally included in the STO-3 trial 1976-1990. After surgery, they were randomized to Tam treatment (40mg for 2 years or no systemic treatment), regardless of classical estrogen receptor α (ER) status. GPER staining was evaluated in carcinoma both as intensity in 5 levels regardless of subcellular localization, and in the plasma membrane in 3 levels. Due to statistical considerations regarding group size, the final analysis was made with intensity in 3 levels and plasma membrane as positive or negative. The Kaplan-Meier method and logrank test (for trend when applicable) were used for survival analysis and Cox regression analysis for obtaining hazard ratios (HR), interaction testing and multivariate modeling. Distant disease-free survival (DDFS) was used as endpoint. Results: Analyzing all patients, we found no association between DDFS and GPER intensity. However, positive plasma membrane staining showed a strong correlation with poor prognosis (HR 1.8 p = 0.002). This was only observed in the ER+ subgroup (ER+ patients HR 2.1, p No obvious difference in tamoxifen response was observed across plasma membrane or intensity groups, and tests for interaction were not significant. A multivariate model including GPER in plasma membrane, ER, histological grade, HER2, tamoxifen and tumor size showed that GPER was an independent prognostic factor (HR 1.6 p = 0.01). Finally we created a group with ER+, progesterone receptor (PR) + patients treated with Tam, as this group today is treated with Tam and thought to have a good response. GPER in the plasma membrane significantly separated this group into an excellent prognosis group and a poor prognosis group (HR 3.3, p = 0.01). The excellent prognosis group, which constitutes more than half of ER+ patients, had a 20 year DDFS of 91% (95% CI 84-95). Conclusion: We found no treatment predictive value of GPER for Tam. However, GPER expressed in the plasma membrane was a strong independent prognostic factor for a poor prognosis in ER+ breast cancer. Used in ER+, PR+, tamoxifen treated patients, it can distinguish patients with an excellent prognosis from patients with a poor outcome that may benefit from additional treatment. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-12.

Purpose: Residual risk of relapse remains a substantial concern for patients with hormone receptor–positive breast cancer, with approximately half of all disease recurrences occurring after five years of adjuvant antiestrogen therapy. Experimental Design: The objective of this study was to examine the prognostic performance of an optimized model of Breast Cancer Index (BCI), an algorithmic gene expression–based signature, for prediction of early (0–5 years) and late (>5 years) risk of distant recurrence in patients with estrogen receptor–positive (ER+), lymph node–negative (LN−) tumors. The BCI model was validated by retrospective analyses of tumor samples from tamoxifen-treated patients from a randomized prospective trial (Stockholm TAM, n = 317) and a multi-institutional cohort (n = 358). Results: Within the Stockholm TAM cohort, BCI risk groups stratified the majority (∼65%) of patients as low risk with less than 3% distant recurrence rate for 0 to 5 years and 5 to 10 years. In the multi-institutional cohort, which had larger tumors, 55% of patients were classified as BCI low risk with less than 5% distant recurrence rate for 0 to 5 years and 5 to 10 years. For both cohorts, continuous BCI was the most significant prognostic factor beyond standard clinicopathologic factors for 0 to 5 years and more than five years. Conclusions: The prognostic sustainability of BCI to assess early- and late-distant recurrence risk at diagnosis has clinical use for decisions of chemotherapy at diagnosis and for decisions for extended adjuvant endocrine therapy beyond five years. Clin Cancer Res; 19(15); 4196–205. ©2013 AACR.

Background: Tamoxifen is a well established treatment for breast cancer, but its long-term effects on the incidence of secondary cancers are not fully evaluated.Material and methods: We have studied 4128 postmenopausal patients with early stage breast cancer who were alive and free of breast cancer recurrence after two years of tamoxifen, and who were randomized to receive totally two or five years of therapy.Results: Compared to patients randomized to two years of tamoxifen the incidence of contralateral breast cancer [hazard ratio (HR) 0.73; 95% CI 0.56–0.96] and of lung cancer (HR 0.45; 95% CI 0.27–0.77), especially squamous cell and small cell lung cancer, were reduced in the five-year group, and similar results were seen when restricting the analysis to the 10-year period after treatment stopped. An increased incidence of endometrial cancer was observed in the five-year group, but the excess risk decreased over time.Conclusion: Further studies of the effects of tamoxifen on the risk of differ...

Reduced or absent Wwox expression has recently been associated with tamoxifen resistance in breast cancer and has also been proposed as a candidate predictive marker for treatment. We aimed to investigate the correlation of Wwox expression with the outcome of tamoxifen treatment by examining tissues from 912 randomized breast cancer patients. Paraffin-embedded tissues from patient tumors were arranged on tissue microarray, and Wwox protein was stained using immunohistochemistry. After microscopic examination, the results were analyzed with Cox regression, Kaplan-Meier survival curves and the log-rank test. In the group of cases having a tumor absent for Wwox expression, there was no difference in recurrence-free survival between treated and untreated patients (P=0.81). For treated cases with a tumor expressing moderate or strong Wwox protein, recurrence-free survival was improved (P=0.001 and P=0.003, respectively). The test for interaction between Wwox and treatment response demonstrated a decreased risk of recurrence for treated patients with a moderate or strong Wwox expression (HR=0.31, 95% CI 0.10-0.98 and HR=0.28, 95% CI 0.08-0.97, respectively). Our results indicate that patients with high expression of Wwox may gain more benefit from treatment with tamoxifen.

Summary Background We compared standard adjuvant anthracycline chemotherapy with anthracycline–taxane combination chemotherapy in women with operable node-positive breast cancer. Here we report the final, 10-year follow-up analysis of disease-free survival, overall survival, and long-term safety. Methods BCIRG 001 was an open label, phase 3, multicentre trial in which 1491 patients aged 18–70 years with node-positive, early breast cancer and a Karnofsky score of 80% or more were randomly assigned to adjuvant treatment with docetaxel, doxorubicin, and cyclophosphamide (TAC) or fluorouracil, doxorubicin, and cyclophosphamide (FAC) every 3 weeks for six cycles. Randomisation was stratified according to institution and number of involved axillary lymph nodes per patient (one to three vs four or more). Disease-free survival was the primary endpoint and was defined as the interval between randomisation and breast cancer relapse, second primary cancer, or death, whichever occurred first. Efficacy analyses were based on the intention-to-treat principle. BCIRG 001 is registered with ClinicalTrials.gov, number NCT00688740. Findings Enrolement took place between June 11, 1997 and June 3, 1999; 745 patients were assigned to receive TAC and 746 patients were assigned to receive FAC. After a median follow-up of 124 months (IQR 90–126), disease-free survival was 62% (95% CI 58–65) for patients in the TAC group and 55% (51–59) for patients in the FAC group (hazard ratio [HR] 0·80, 95% CI 0·68–0·93; log-rank p=0·0043). 10-year overall survival was 76% (95% CI 72–79) for patients in the TAC group and 69% (65–72) for patients in the FAC group (HR 0·74, 0·61–0·90; log-rank p=0·0020). TAC improved disease-free survival relative to FAC irrespective of nodal, hormone receptor, and HER2 status, although not all differences were significant in these subgroup analyses. Grade 3–4 heart failure occurred in 26 (3%) patients in the TAC group and 17 (2%) patients in the FAC group, and caused death in two patients in the TAC group and four patients in the FAC group. A substantial decrease in left ventricular ejection fraction (defined as a relative decrease from baseline of 20% or more) was seen in 58 (17%) patients who received TAC and 41 (15%) patients who received FAC. Six patients who received TAC developed leukaemia or myelodysplasia, as did three patients who received FAC. Interpretation Our results provide evidence that the initial therapeutic outcomes seen at the 5-year follow-up with a docetaxel-containing adjuvant regimen are maintained at 10 years. However, a substantial percentage of patients had a decrease in left ventricular ejection fraction, probably caused by anthracycline therapy, which warrants further investigation. Funding Sanofi.

Cancer‐associated fibroblasts (CAFs) regulate tumour growth, metastasis and response to treatment. Recent studies indicate the existence of functionally distinct CAF subsets. Suggested mechanisms whereby CAFs can impact on treatment response include paracrine signalling affecting cancer cell drug sensitivity and effects on tumour drug uptake. PDGFRβ is an important regulator of fibroblasts. Experimental studies have linked PDGFRβ‐positive fibroblasts to metastasis and also to reduced tumour drug uptake. This study has investigated the potential role of PDGFRβ‐positive fibroblasts in response to adjuvant tamoxifen treatment of breast cancer. Analyses of two breast cancer collections from randomised studies analysing adjuvant tamoxifen treatment in early breast cancer demonstrated significant benefit of tamoxifen in the group with low stromal PDGFRβ, which was not observed in the group with high stromal PDGFRβ. In general terms these findings provide novel evidence, derived from analyses of randomised clinical studies, of response‐predictive capacity of a marker‐defined subset of CAFs and, more specifically, identify stromal PDGFRβ as a marker related to tamoxifen benefit in early breast cancer.

Adherence to long-term pharmacological treatment for chronic conditions is often less than optimal. Till date, a limited number of population-based studies have assessed adherence to adjuvant hormonal therapy in breast cancer, a therapy with proven benefits in terms of reductions of recurrence and mortality. We aimed to examine rates of adherence and early discontinuation in Sweden where prescribed medications are subsidized for all residents and made available at reduced out-of-pocket costs. Individual-level data were obtained from Regional Clinical Quality Breast Cancer Registers, the Swedish Prescribed Drug Register, and several other population-based registers. Multivariate logistic regression was used to analyze factors associated with adherence to prescribed medication for a period of 3 years. Between January 1 and December 31, 2005, 1,741 patients in central Sweden were identified with estrogen receptor positive breast cancer, and at least one prescription dispensation of either tamoxifen or an aromatase inhibitor. Of these women, 1,193 (69%) were fully adherent to therapy for 3 years (medication possession ratio of 80% or higher and a maximum of 180 days between refills). During the 3-year follow-up, 215 women (12%) had prematurely discontinued therapy. Adherence was positively associated with younger age, large tumor size, being married, and being born in the Nordic countries, while no clear association was observed with education or income. During the 3 years of follow-up, 31% of women were non-adherent to therapy. Further efforts must be undertaken to promote adherence over the entire recommended treatment period.

Background: CXCL10 is a chemokine with chemo attractant properties which signals through G protein-coupled receptor CXCR3. At least two reported isoforms exists; CXCR3-A and CXCR3-B. CXCL10 is involved in the recruitment of leucocytes, immune modulation and angiogenesis. In animal models CXCL10 inhibits tumour growth, metastase formation and inhibits angiogenesis. The receptors have opposite features; CXCR3-A mediates proliferative or anti-apoptotic response and CXCR3-B mediates growth inhibition and apoptosis in response to ligand binding. The aim of this study was to investigate the role of CXCL10 and CXCR3-A as prognostic or tamoxifen treatment predictive factors in breast cancer. Material and Methods: A randomized tamoxifen trial comprising 1,780 breast cancer patients was conducted in Stockholm, Sweden, 1976–1990. All patients had lymph node negative primary breast cancer and were postmenopausal at the time of diagnosis. The patients were randomized to tamoxifen or no endocrine treatment. We analyzed the protein expression of CXCL10 and the receptor CXCR3A with immunohistochemistry using tissue microarrays, which were constructed from paraffin blocks originating from 912 patients. CXCL10 and CXCR3A could be scored in 793 (87%) and 735 (81%), respectively. Results: High expression of CXCL10 was associated with significant benefit of tamoxifen treatment concerning local recurrence and breast cancer survival (P=0.02 and P=0.008). For patients with high CXCL10 expression, tamoxifen decreased the risk concerning local recurrence (rate ratio (RR) = 0.56, 95% C.I. 0.33−0.97, P=0.0029) and breast cancer survival (RR 0.6 95% C.I. 0.39−0.97, P=0.023). High expression of CXCR3-A was associated with significant benefit of tamoxifen treatment concerning total recurrence and breast cancer survival (P=0.00001 and P=0.004, respectively). For patients with high CXCR3-A expression, tamoxifen decreased the risk of total recurrence (RR 0.54 95% C.I. 0.35−0.83, P=0.005) and breast cancer survival (RR 0.49 95% C.I. 0.35−0.69, P=0.00003). On the opposite, in the cohort of patients with no endocrine treatment and high CXCR3-A expression, there was an increased risk of total recurrence (P=0.003). (RR 2.07 95% C.I. 1.18−3.61, P=0.011). Conclusions: This study indicates that high expression of CXCL10 can be used as predictive markers for tamoxifen treatment. Further, high expression of CXCR3-A is related to bad prognosis and predicts tamoxifen treatment in breast cancer patients. This needs to be further evaluated. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-06-06.

Treatment of metastatic breast cancer (MBC) has evolved during the last decades but it is largely unknown whether this has led to improved survival in the general MBC population. Based on the regional, population-based breast cancer registry, we identified 5,463 patients diagnosed with MBC in Stockholm County during 1979–2004. Patients were divided into five cohorts based on the year of first MBC diagnosis and observed and relative survival were compared across the cohorts after adjustment for potential confounders. A significant trend of better survival over time was demonstrated for patients 60 years or younger (P < 0.001, by log-rank test for trend), but not for older patients (P = 0.12) or for the whole MBC population (P = 0.13). The adjusted observed survival of patients ≤60 years was significantly improved in the 2000–2004 cohort (P < 0.001, hazard ratio = 0.7, 95% confidence interval = 0.58–0.84), corresponding to a clinically significant increase of median survival with more than 3 months and absolute increase of 5-year survival with 8% or more compared to previous periods. Similarly, relative survival analysis indicated a 31% decreased mortality for the younger subpopulation in the 2000–2004 cohort (P < 0.001). Systemic adjuvant treatment was a negative prognostic factor after distant recurrence. Treatment advancements in MBC are not reflected by better survival for the whole MBC population. An improvement is only observed after the year 2000 and is restricted to younger patients.

Objective: The aims of this study were to generate new knowledge about factors predicting return to work (RTW) among women treated for early-stage breast cancer, and about changes in life satisfaction, and coping, and to examine the association between these concepts and RTW. Methods and Participants: A cohort of 102 women aged 18-64 were assessed six weeks, six months, and ten months after surgery using data from questionnaires and medical files. Results: Factors independently predicting no RTW at six months were: chemotherapy, > 30 days of sick leave during the previous 12 months, low satisfaction with activities of dai ly living, and not having been born in Sweden. No RTW at ten months was predicted by irradiation to breast/chest wall and regio nal nodes, and low satisfaction with vocational situation. Global life satisfaction was higher among the working women, both six months after surgery and ten months after surgery. The working women used more positive coping resources as compared to the sick-listed women, particularly sick-listed women treate d with chemotherapy. Conclusion: Factors associated with RTW appear to include not only treatment-related factors such as chemotherapy and irradiation, but also psychosocial factors such as life sat isfaction and coping resources. With increased understanding of the complex factors related to RTW after a breast cancer diagnosis, it will be possible to identify and support survivors who are at risk of being marginalized from the labor market.

Background: Ovarian ablation improves survival in premenopausal women with early breast cancer, but the potential added value by luteinizing hormone-releasing hormone agonists (LHRH-a) to tamoxifen, is still not clear. There has been lack of data reported separately for patients who underwent randomization to both LHRH-a and tamoxifen. Patients and Methods: In Stockholm, 927 patients assigned to the Zoladex in Premenopausal Patients (ZIPP) trial, were included in a 2 x 2 factorial randomization to goserelin (3.6 mg subcutaneously, q 28d), tamoxifen (40 mg daily), the combination of goserelin and tamoxifen or no endocrine therapy for two years, with or without chemo-and/or radiotherapy. The trial was designed to examine the effect of goserelin and the role of interaction between goserelin and tamoxifen in adjuvant therapy of premenopausal breast cancer. We examined as well, the impact of different estrogen receptor (ER) content on treatment effect. The definition of first event was breast cancer recurrence, contra lateral breast cancer or death. The ER content was determined by isoelectric focusing on polyacrylamide gel and receptor values normalized to DNA content. Results: After a median follow up of 12.3 years, goserelin reduced the risk of first event by 32% (p=0.005) in the absence of tamoxifen and tamoxifen reduced the risk by 27% (p=0.018) in the absence of goserelin. The combined goserelin and tamoxifen treatment reduced the risk by 24% (p=0.021) and there was a significant interaction between goserelin and tamoxifen (p=0.025). In highly ER positive tumours, there were 29% fewer events among goserelin treated (p=0.044) and a trend towards greater risk reduction depending on the level of ER content. The greatest risk reduction from goserelin treatment was observed among those not receiving tamoxifen (HR: 0.52, p=0.007). For tamoxifen, there was not a significant risk reduction at different ER levels, but there was a trend towards interaction between goserelin and tamoxifen effect among the highly ER positive (p=0.076). Discussion: In this strictly randomized cohort of endocrine responsive premenopausal breast cancer, goserelin as well as tamoxifen, reduces the risk of recurrence. However, the combination of goserelin and tamoxifen is not superior to either modality alone. The effect of goserelin seems to be modified by ER levels, whereas tamoxifen effect is not. Women with strongly estrogen receptor positive tumours may benefit more from goserelin treatment. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr S1-5.

516Background: An increasing body of evidence from extended endocrine therapy trials underscores the unmet need to manage risk-benefit at the individual patient (pt) level. Breast Cancer Index (BCI...

541Background: Breast cancer patients with estrogen receptor (ER)-positive disease have a continuous long-term risk for fatal breast cancer spanning more than 20 years, but the biological factors i...

Purpose: Estrogens have great significance in the development of breast cancer. After menopause, most estrogen biosynthesis is done in peripheral tissue, and the main enzymes involved in balancing the amount of estrone against estradiol are 17β-hydroxysteroid dehydrogenases (17HSD). The aim of this study was to investigate the prognostic and tamoxifen predictive values of 17HSD1 and 17HSD2 expression. Experimental Design: Tumors from low-risk breast cancer patients randomized to adjuvant tamoxifen therapy or no adjuvant treatment were analyzed with immunohistochemistry to investigate protein expression of 17HSD1 and 17HSD2 in 912 cases. All patients had lymph node-negative breast cancer and were postmenopausal at the time of diagnosis. Results: Low 17HSD1 expression was associated with significant benefit from tamoxifen treatment among patients with estrogen receptor (ER)-positive tumors (P < 0.001). For patients with a 17HSD1 score not exceeding that of 17HSD2, tamoxifen increased the rate of distant recurrence-free survival (hazard ratio, 0.37; 95% confidence interval, 0.23-0.60) and breast cancer-specific survival (hazard ratio, 0.30; 95% confidence interval, 0.16-0.54), whereas no apparent effect was observed when the 17HSD1 score was higher than that of 17HSD2. The interaction was significant for both distant recurrence-free survival (P = 0.036) and breast cancer-specific survival (P = 0.014). In the cohort of systemically untreated patients, no prognostic importance was observed. Conclusions: This is the first report that clearly distinguishes between the prognostic and predictive importance of 17HSD1 and 17HSD2 in ER-positive breast cancer treated with or without tamoxifen. Our data suggest that the 17HSD1/17HSD2 ratio might be useful as a predictive factor for tamoxifen treatment in ER-positive breast cancer patients.

The most common female cancer in Western countries is breast cancer and women diagnosed with this disease are often under 65 years old. With increasing prevalence of survivors it is important to shed light on problems facing these women after diagnosis and treatment. The aim of this study was to assess factors predicting return to work (RTW) in women with early-stage breast cancer.A cohort of 102 women aged 18-64 with early-stage breast cancer who had undergone curative primary surgery with or without systemic adjuvant therapy were followed for 10 months using data from questionnaires and medical files.Ten months after primary surgery, 59% of the women had returned to work while 41% were sick-listed part-time or full-time. After adjusting for age, health status, life satisfaction, vocational situation, and irradiation to the breast/chest wall and regional nodes, a multivariate logistic regression revealed the following factors as being negatively associated with RTW: a high-demand job (OR=0.1, 95% CI 0.0-0.8), axillary node dissection (OR=0.1, 95% CI 0.0-0.6), and treatment with chemotherapy (OR=0.1, 95% CI 0.0-0.7).Treatment factors and high demands at work play an important role in RTW for women with early-stage breast cancer.

Recent studies on the pattern of gene expression in estrogen receptor positive and negative tumours have revealed profound differences according to receptor status. However, it remains unclear if these differences reflect phenotypic traits in addition to sensitivity to endocrine therapy. This paper describes the long-term pattern of disease recurrence among ca. 2,600 pre- and post-menopausal patients with primary breast cancer according to estrogen receptor status. The study was based on patients with an operable, invasive breast cancer entered in one of three controlled clinical trials conducted by the Stockholm Breast Cancer Group. We selected those 2,562 patients who had been randomly allocated between adjuvant tamoxifen and no adjuvant systemic therapy. These patients had a known estrogen receptor status. Tamoxifen reduced locoregional (8.8% vs. 12.4%, hazard ratio (HR), 0.66; 95% CI, 0.52–0.83; P = 0.001, distant recurrences (17.2% vs. 20.2%, HR, 0.81; CI, 0.68–0.97; P = 0.018, as well as breast cancer death (18.7% vs. 23.7%, HR, 0.78; CI, 0.67–0.92; P = 0.002). Among patients not allocated to tamoxifen there was no significant differences in term of neither locoregional (12.4% vs. 12.4%, HR, 1; CI, 0.72–1.41; P = 0.98), nor distant metastases (18.5% vs. 20.7%, HR, 1.11;CI, 0.85–1.45; P = 0.46) according to ER status. The pattern of metastases was not different in ER positive comparison with ER negative. The results showed that the mentioned substantial differences in terms of gene expression appeared mainly to be related to endocrine sensitivity and not to metastatic potential. However, a slight advantage during the first five years for the ER positive versus ER negative patients in terms of cumulative incidence of events, suggested that ER negativity in some cases is correlated with an increased tumour growth rate.

The HER receptors are of therapeutic and prognostic significance in breast cancer, and their function is modulated by cytoplasmic tyrosine kinases like PTK6 (brk). We performed a retrospective study on archival breast cancer samples from patients with long follow-up and compared the protein expression between individual HERs and between HERs and the PTK6. Univariate and multivariate analyses were used to study the prognostic value of parameters. Metastases-free survival of patients for longer than 240 months was inversely associated (Por =0.05) with nodal status, tumour size, and oestrogen receptor status, but was also directly associated with high protein expression levels of HER4 and PTK6 in Kaplan-Meier analysis. In multivariate analysis for metastases-free survival of240 months, the stepwise selected parameters were tumour size (relative risk 3.1), PTK6 expression (0.4), and number of positive lymph nodes (1.2). Furthermore, we demonstrated a timedependence of the prognostic value attributed to the parameters. The HER receptors (HER2,4), but not PTK6, were independent prognostic markers for metastases-free survival at 60 months, whereas at 240 months PTK6 is the strongest prognostic marker. We demonstrate that PTK6 is a prognostic marker of metastases-free survival in breast cancer, and is independent of the classical morphological and molecular markers of lymph node involvement, tumour size, and HER2 status.

Purpose: Estrogen-related receptor alpha (ERRα) signaling has recently been implicated in breast cancer. We investigated the clinical value of ERRα in randomized cohorts of tamoxifen-treated and adjuvant-untreated patients. Experimental Design: Cox proportional hazards regression was used to evaluate the significance of associations between ERRα gene expression levels and patient DMFS in a previously published microarray dataset representing 2,000 breast tumor cases derived from multiple medical centers worldwide. The 912 tumors used for immunostaining were from a tamoxifen-randomized primary breast cancer trial conducted in Stockholm, Sweden, during 1976–1990. Mouse model was used to study the effect of tamoxifen treatment on lung colonization of MDA-MB-231 control cells and MDA-MB-231 cells with stable knockdown of ERRα. The phenotypic effects associated with ERRα modulation were studied using immunoblotting analyses and wound-healing assay. Results: We found that in ER-negative and triple-negative breast cancer (TNBC) adjuvant-untreated patients, ERRα expression indicated worse prognosis and correlated with poor outcome predictors. However, in tamoxifen-treated patients, an improved outcome was observed with high ERRα gene and protein expression. Reduced ERRα expression was oncogenic in the presence of tamoxifen, measured by in vitro proliferation and migration assays and in vivo metastasis studies. Conclusions: Taken together, these data show that ERRα expression predicts response to tamoxifen treatment, and ERRα could be a biomarker of tamoxifen sensitivity and a prognostic factor in TNBC. Clin Cancer Res; 22(6); 1421–31. ©2015 AACR.

The Zoladex In Pre-menopausal Patients (ZIPP) study was designed to determine whether addition of goserelin ('Zoladex') and/or tamoxifen to adjuvant therapy (radiotherapy and/or chemotherapy), provided benefit to pre- or peri-menopausal women with operable, early breast cancer. A combined analysis of four randomised trials using a core protocol was performed. Patients (n = 2710) were randomised into a 2 x 2 factorial trial based on goserelin and tamoxifen (n = 1800) or randomised to receive goserelin or not (n = 910; some received elective tamoxifen) for 2 years. The analysis presented here compares women who did (n = 1354) or did not (n = 1356) receive goserelin. After a median follow-up of 5.5 years, goserelin provided a significant benefit for event-free survival (hazard ratio [HR] 0.80; 95% confidence interval [CI] 0.69, 0.92; P = 0.002) and overall survival (HR 0.81; 95% CI 0.67, 0.99; P = 0.038). Goserelin was well tolerated. These data show that the addition of goserelin to standard adjuvant therapy is more effective than standard therapy alone in pre-menopausal women with early breast cancer.