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Background: Adenomyoepithelial tumours and myoepithelial carcinomas of the breast are primarily defined by the presence of neoplastic cells with a myoepithelial immunophenotype. Current classification schemes are based on purely descriptive features and an assessment of individual prognosis is still problematic.

BackgroundProliferative activity (Ki-67 Labelling Index) in breast cancer increasingly serves as an additional tool in the decision for or against adjuvant chemotherapy in midrange hormone receptor positive breast cancer. Ki-67 Index has been previously shown to suffer from high inter-observer variability especially in midrange (G2) breast carcinomas. In this study we conducted a systematic approach using different Ki-67 assessments on large tissue sections in order to identify the method with the highest reliability and the lowest variability.Materials and MethodsFive breast pathologists retrospectively analyzed proliferative activity of 50 G2 invasive breast carcinomas using large tissue sections by assessing Ki-67 immunohistochemistry. Ki-67-assessments were done on light microscopy and on digital images following these methods: 1) assessing five regions, 2) assessing only darkly stained nuclei and 3) considering only condensed proliferative areas (‘hotspots’). An individual review (the first described assessment from 2008) was also performed. The assessments on light microscopy were done by estimating. All measurements were performed three times. Inter-observer and intra-observer reliabilities were calculated using the approach proposed by Eliasziw et al. Clinical cutoffs (14% and 20%) were tested using Fleiss’ Kappa.ResultsThere was a good intra-observer reliability in 5 of 7 methods (ICC: 0.76–0.89). The two highest inter-observer reliability was fair to moderate (ICC: 0.71 and 0.74) in 2 methods (region-analysis and individual-review) on light microscopy. Fleiss’-kappa-values (14% cut-off) were the highest (moderate) using the original recommendation on light-microscope (Kappa 0.58). Fleiss’ kappa values (20% cut-off) were the highest (Kappa 0.48 each) in analyzing hotspots on light-microscopy and digital-analysis. No methodologies using digital-analysis were superior to the methods on light microscope.ConclusionOur results show that all methods on light-microscopy for Ki-67 assessment in large tissue sections resulted in a good intra-observer reliability. Region analysis and individual review (the original recommendation) on light-microscopy yielded the highest inter-observer reliability. These results show slight improvement to previously published data on poor-reproducibility and thus might be a practical-pragmatic way for routine assessment of Ki-67 Index in G2 breast carcinomas.

BackgroundHistopathological B3 lesions after minimal invasive breast biopsy (VABB) are a particular challenge for the clinician, as there are currently no binding recommendations regarding the subsequent procedure.PurposeTo analyze all B3 lesions, diagnosed at VABB and captured in the national central Swiss MIBB database and to provide a data basis for further management in this subgroup of patients.Material and MethodsAll 9,153 stereotactically, sonographically, or magnetic resonance imaging (MRI)-guided vacuum-assisted breast biopsies, performed in Switzerland between 2009 and 2011, captured in a central database, were evaluated. The rate of B3 lesions and the definitive pathological findings in patients who underwent surgical resection were analyzed.ResultsThe B3 rate was 17.0% (1532 of 9000 biopsies with B classification). Among the 521 lesions with a definitive postoperative diagnosis, the malignancy rate (invasive carcinoma or DCIS) was 21.5%. In patients with atypical ductal hyperplasia, papillary lesions, flat epithelial atypia, lobular neoplasia, and radial scar diagnosed by VABB, the malignancy rates were 25.9%, 3.1%, 18.3%, 26.4%, and 11.1%, respectively.ConclusionB3 lesions, comprising 17%, of all analyzed biopsies, were common and the proportion of malignancies in those lesions undergoing subsequent surgical excision was high (21.5%).

Background: The BIG 1-98 trial, a large international Phase III study, evaluated letrozole (Let) for 5 years (n=1546) vs. Let for 2 years followed by tamoxifen (Tam) for 3 years (L→T; n=1540) and vs. Tam for 2 years followed by Let for 3 years (T→L; n=1548) as initial adjuvant endocrine therapy for postmenopausal women with hormone receptor-positive breast cancer. Patients with HER2-positive disease did not receive trastuzumab. Efficacy results were presented in SABCS 2008 and showed that neither of the sequential therapy arms significantly improved disease-free survival (DFS) compared with letrozole alone. Centrally-assessed ER, PgR and HER2 have now been evaluated as potential predictive factors for treatment selection.Methods: Tumor blocks for 3975 of the 4634 (86%) patients on these three treatment arms were centrally collected and assessed by the IBCSG Central Pathology Laboratory. The tumors were evaluated for ER and PgR content by immunohistochemistry (IHC), and for HER2 immunoreactivity by IHC and by FISH for IHC 1+ or 2+ tumors. DFS according to centrally-assessed ER, PgR and HER2 status was analyzed using multivariable Cox modeling. STEPP methodology was used to explore patterns of DFS differences according to quantitative values of receptor levels (% staining cells).Results: Upon central review, 3885 tumors were confirmed to express ER and are the focus of this analysis. PgR expression did not predict differential treatment effects among the 3 treatment arms. With only 240 (6.2%) HER2-positive tumors, there was a suggestion of differential treatment benefit relative to HER2 status, in particular of a benefit of Let for 5 yrs over Tam→Let in HER2-positive tumors.Discussion: Given the caveat of a low prevalence of HER2-positive tumors and absence of HER2-directed therapy in the BIG 1-98 trial population, there is a suggestion that Let for 5 years may be a better option than a sequence of Tam and Let among women with HER2-positive tumors. Thus it may be better to initiate and continue treatment of endocrine-responsive, HER2+ tumors with Let rather than a sequence of Tam and Let. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 76.