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Purpose: The International Ki67 Working Group (IKWG) has developed training for immunohistochemistry (IHC) scoring reproducibility and recommends cut points of ≤ 5% and ≥ 30% for prognosis in ER+, HER2−, stage I/II breast cancer. We examined scoring reproducibility following IKWG training and evaluated these cut points for selecting patients for further testing with the 21-gene Recurrence Score (RS) assay. Methods: We included 307 women aged 50+ years with node-negative, ER+PR+HER2− breast cancer and with available RS results. Slides from the diagnostic biopsy were stained for Ki67 and scored using digital image analysis (IA). Two IHC pathologists underwent IKWG training and visually scored slides, blinded to each other and IA readings. Interobserver reproducibility was examined using intraclass correlation (ICC) and Kappa statistics. Results: Depending on reader, 8.8–16.0% of our cohort had Ki67 ≤ 5% and 11.4–22.5% had scores ≥ 30%. The ICC for Ki67 scores by the two pathologists was 0.82 (95% CI 0.78–0.85); it was 0.79 (95% CI 0.74–0.83) for pathologist 1 and IA and 0.76 (95% CI 0.71–0.80) for pathologist 2 and IA. For Ki67 scores ≤ 5%, the percentages with RS < 26 were 92.6%, 91.8%, and 90.9% for pathologist 1, pathologist 2, and IA, respectively. For Ki67 scores ≥ 30%, the percentages with RS ≥ 26 were 41.5%, 51.4%, and 27.5%, respectively. Conclusion: The IKWG's Ki67 training resulted in moderate to strong reproducibility across readers but cut points had only moderate overlap with RS cut points, especially for Ki67 ≥ 30% and RS ≥ 26; thus, their clinical utility for a 21-gene assay testing pathway remains unclear. [ABSTRACT FROM AUTHOR]

Purpose: Reports suggest that up to 50% of women with hormone receptor-positive (HR+) breast cancer (BC) do not complete the recommended 5 years of adjuvant endocrine therapy (AET). We examined the impact of an outreach program at Kaiser Permanente Northern California (KPNC) on adherence and discontinuation of AET among patients who initiated AET. Methods: We assembled a retrospective cohort of all KPNC patients diagnosed with HR+, stage I–III BC initiating AET before (n = 4287) and after (n = 3580) implementation of the outreach program. We compared adherence proportions and discontinuation rates before and after program implementation, both crude and adjusted for age, race/ethnicity, education, income, and stage. We conducted a pooled analysis of data from six Cancer Research Network (CRN) sites that had not implemented programs for improving AET adherence, using identical methods and time periods, to assess possible secular trends. Results: In the pre-outreach period, estimated adherence in years 1, 2, and 3 following AET initiation was 75.2%, 71.0%, and 67.3%; following the outreach program, the estimates were 79.4%, 75.6%, and 72.2% (p-values <.0001 for pairwise comparisons). Results were comparable after adjusting for clinical and demographic factors. The estimated cumulative incidence of discontinuation was 0.22 (0.21–0.24) and 0.18 (0.17–0.19) at 3 years for pre- and post-outreach groups (p-value <.0001). We found no evidence of an increase in adherence between the study periods at the CRN sites with no AET adherence program. Conclusion: Adherence and discontinuation after AET initiation improved modestly following implementation of the outreach program. [ABSTRACT FROM AUTHOR]

Purpose: A majority of women with ductal carcinoma in situ (DCIS) receive breast-conserving surgery (BCS) but then face a risk of ipsilateral breast tumor recurrence (IBTR) which can be either recurrence of DCIS or invasive breast cancer. We developed a score to provide individualized information about IBTR risk to guide treatment decisions.Methods: Data from 2762 patients treated with BCS for DCIS at centers within the National Comprehensive Cancer Network (NCCN) were used to identify statistically significant non-treatment-related predictors for 5-year IBTR. Factors most associated with IBTR were estrogen-receptor status of the DCIS, presence of comedo necrosis, and patient age at diagnosis. These three parameters were used to create a point-based risk score. Discrimination of this score was assessed in a separate DCIS population of 301 women (100 with IBTR and 200 without) from Kaiser Permanente Northern California (KPNC).Results: Using NCCN data, the 5-year likelihood of IBTR without adjuvant therapy was 9% (95% CI 5–12%), 23% (95% CI 13–32%), and 51% (95% CI 26–75%) in the low, intermediate, and high-risk groups, respectively. Addition of the risk score to a model including only treatment improved the C-statistic from 0.69 to 0.74 (improvement of 0.05). Cross-validation of the score resulted in a C-statistic of 0.76. The score had a c-statistic of 0.67 using the KPNC data, revealing that it discriminated well.Conclusions: This simple, no-cost risk score may be used by patients and physicians to facilitate preference-based decision-making about DCIS management informed by a more accurate understanding of risks. [ABSTRACT FROM AUTHOR]

We examined the clinical/pathologic features of ipsilateral second breast cancers (IP-SBCs) following breast-conserving surgery (BCS) for DCIS among community-treated patients and ascertained the degree of correlation between the features of index DCIS and IP-SBC events. From a Cancer Research Network cohort of DCIS patients diagnosed 1990-2001 and treated with BCS, we identified women who subsequently developed an ipsilateral DCIS or invasive breast cancer. All index DCIS tumors underwent expert pathology review. Pathologic characteristics of IP-SBCs were abstracted from available medical records. Logistic regression was used to examine associations between pathologic characteristics and identify factors associated with invasive versus non-invasive IP-SBC. Of 1969 DCIS patients, 182 developed an IP-SBC within a median of 38 months (range 6-160). IP-SBCs were slightly more commonly non-invasive (53 %) versus invasive (47 %). Of invasive IP-SBCs, 31 % were high grade, 67 % were <20 mm, 74 % were estrogen receptor positive, 7 % were HER2 positive, and 16 % were node positive. Of non-invasive IP-SBCs, 33 % were high grade. Comparing index DCIS and IP-SBC specimens, there was moderate-high correlation for HR status and grade. Among patients with IP-SBCs, those who were younger and whose index DCIS tumors were HR negative had shorter intervals (within 3 years) between index and IP-SBC diagnoses. No index DCIS feature was statistically significantly associated with an IP-SBC that was invasive versus non-invasive. Understanding the characteristics of SBCs and identifying correlations between these and index DCIS events could influence treatment choices for DCIS, and may help patients and providers develop treatment paradigms for SBCs. [ABSTRACT FROM AUTHOR]

We aimed to identify clinicopathologic factors associated with local recurrence (LR) in a large population of DCIS patients treated with breast-conserving therapy between 1990-2001 in three health plans. Regression methods were used to estimate relative risks (RR) of LR. Among 2,995 patients, 325 had a LR [10.9 %; median follow-up 4.8 years (range 0.5-15.7)]. After adjusting for health plan and treatment, risk of LR was increased among women <45 years (RR = 2.1, 95 % CI 1.5-2.8), African-Americans (RR = 1.6; 95 % CI 1.1-2.1) and those with DCIS detected because of signs/symptoms (RR = 1.6; 95 % CI 1.2-2.0). After also adjusting for age and diagnosis year, pathologic features associated with increased LR were larger lesion size (RR = 2.9 for ≥20 low power fields of DCIS; 95 % CI 1.6-5.6) and involved (RR = 2.9; 95 % CI 1.6-5.2), or close margins (RR = 2.4; 95 % CI 1.6-3.8). Presentation with symptoms/signs was associated with increased risk of invasive recurrence; while African-American race, larger tumor size, and involved/close tumor margins were more strongly associated with increased risk of DCIS recurrence. Our findings suggest some risk factors differ for non-invasive and invasive LRs and that most factors are only moderately associated with increased LR risk. Future research efforts should focus on non-clinicopathologic factors to identify more powerful risk factors for LR. [ABSTRACT FROM AUTHOR]