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Background:The St Gallen surrogate definition of the intrinsic subtypes of breast cancer consist of five subgroups based on estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor type 2 (HER2), and Ki-67. PgR and Ki-67 are used for discriminating between the ‘Luminal A-like’ and ‘Luminal B-like (HER2-negative)’ subtypes. Histological grade (G) has prognostic value in breast cancer; however, its relationship to the St Gallen subtypes is not clear. Based on a previous pilot study, we hypothesized that G could be a primary discriminator for ER-positive/HER2-negative breast cancers that were G1 or G3, whereas Ki-67 and PgR could provide additional prognostic information specifically for patients with G2 tumors. To test this hypothesis, a larger patient cohort was examined. Patients and methods:Six hundred seventy-one patients (≥35 years of age, pT1-2, pN0-1) with ER-positive/HER2-negative breast cancer and complete data for PgR, Ki-67, G, lymph node status, tumor size, age, and distant disease-free survival (DDFS; median follow-up 9.2 years) were included. Results:‘Luminal A-like’ tumors were mostly G1 or G2 (90%) whereas ‘Luminal B-like’ tumors were mostly G2 or G3 (87%) and corresponded with good and poor DDFS, respectively. In ‘Luminal B-like’ tumors that were G1 (n = 23), no metastasis occurred, whereas 14 of 40 ‘Luminal A-like’ tumors that were G3 metastasized. In the G2 subgroup, low PgR and high Ki-67 were associated with an increased risk of distant metastases, hazard ratio (HR) and 95% confidence interval (CI) 1.8 (0.95–3.4) and 1.5 (0.80–2.8), respectively. Conclusions:Patients with ER-positive/HER2-negative/G1 breast cancer have a good prognosis, similar to that of ‘Luminal A-like’, while those with ER-positive/HER2-negative/G3 breast cancer have a worse prognosis, similar to that of ‘Luminal B-like’, when assessed independently of PgR and Ki-67. Therapy decisions based on Ki-67 and PgR might thus be restricted to the subgroup G2. [ABSTRACT FROM PUBLISHER]

Background. Oestrogen receptor (ER) status is important for the choice of systemic treatment of breast cancer patients. However, most data from randomised trials on the effect of adjuvant endocrine therapy according to ER status are based on the cytosol methods. Comparisons with immunohistochemical methods have given similar results. The aim of the present study was to examine whether different ER antibodies and heat-induced epitope retrieval (HIER) methods influence the prevalence of ER-positivity in primary breast cancer. Material and methods. This study is based on patients included in a clinical trial designed to compare the effect of two years of adjuvant tamoxifen versus no adjuvant systemic treatment in premenopausal women. From 1986 to 1991, 564 patients from two study centres in Sweden were enrolled and randomised. Patients were randomised independently of ER status. In the present study, ER status was assessed on tissue microarrays with the three different ER antibody/HIER combinations: 1D5 in citrate pH 6 (n = 390), SP1 in Tris pH 9 (n = 390) and PharmDx in citrate pH 6 (n = 361). Results. At cut-offs of 1% and 10%, respectively, the prevalence of ER-positivity was higher with SP1 (75% and 72%) compared with 1D5 (68% and 66%) and PharmDx (66% and 62%). At these cut-offs, patients in the discordant groups (SP1-positive and 1D5-negative) seem to have a prognosis intermediate between those of the double-positive and double-negative groups. Comparison with the ER status determined by the cytosol-based methods in the discordant group also showed an intermediate pattern. The repeatability was good for all antibodies and cut-offs, with overall agreement ≥ 93%. Conclusion. The present study shows that the choice of antibody and HIER method influences the prevalence of ER-positivity. We suggest that this be taken into consideration when choosing a cut-off for clinical decision making. [ABSTRACT FROM AUTHOR]

Background. HER2 is a treatment predictive factor for the effect of trastuzumab and associated with poor prognosis in breast cancer. The analysis of HER2 must be performed with good quality, with regard to both the immunohistochemical (IHC) and in situ hybridization (ISH) analysis. Material and methods. A tissue microarray (TMA) including 11 breast cancer samples was sent twice (once in 2005 and again in 2006) to 24 pathology departments in Sweden. A questionnaire was also sent to the departments in 2006. Results. With IHC, all departments reported the same results (0/1+ vs. 2+ vs. 3 + ) for three (2005) and six samples (2006). The mean kappa-value increased from 0.67 to 0.77, indicating a good reproducibility at both occasions. With fluorescence-ISH (FISH), the 11 departments using this technique reported the same results (amplified vs. normal) for nine (2005) and ten samples (2006). The mean kappa-value showed very good reproducibility both 2005 and 2006 (0.92 and 0.96, respectively). Based on the answers from the participating departments, the questionnaire revealed that 31% of primary breast cancer diagnosed in 2006 (n = 5 043) were 2 + /3+. FISH analysis of 2+ confirmed 12% of the samples to be amplified. The corresponding figure for 3 + was 90%. In total, 14.3% of the samples were HER2 positive (2+ and amplified, or 3 + ). Discussion. The results obtained in this study indicate that the reproducibility for HER2 analysis is good (IHC) and very good (FISH) between the pathology departments in Sweden using TMA-based tumor samples. In 2006, 14.3% of invasive breast cancers were HER2 positive. [ABSTRACT FROM AUTHOR]