Pathology of BRCA1- and BRCA2-associated Breast Cancers: Known and Less Known Connections.

INTRODUCTION: BRCA1/BRCA2 mutation carriers indefinitely comprise a distinct group of patients with breast cancer (BC), with their tumors displaying specific pathologic characteristics. Although these connections are known, they are not fully elucidated. We therefore sought to investigate the clinicopathologic characteristics and overall survival of Greek patients with BC carrying BRCA1/BRCA2 mutations. PATIENTS AND METHODS: Greek patients with BC diagnosed between 1999 and 2016, fulfilling the National Comprehensive Cancer Network criteria for genetic testing, were analyzed for BRCA1/BRCA2 mutations by Sanger sequencing or by a 94-gene panel. Medical records and pathology reports were retrospectively reviewed to retrieve patient and tumor baseline characteristics. Potential associations with mutation status were assessed using the Fisher exact, Pearson χ2, and Mann-Whitney tests. RESULTS: Of 2096 selected patients with BC, we identified 297 (14.2%) BRCA1 and 88 (4.2%) BRCA2 carriers. The mean age at BC diagnosis was 40 and 42.6 years, respectively (P = .02). Tumor histologic subtypes in BRCA1 and BRCA2 carriers were predominantly ductal (79%) followed by medullary (10%), and ductal (72%) followed by lobular (15%), respectively. A significantly higher percentage of BRCA2 tumors were human epidermal growth factor receptor 2-positive, compared with BRCA1 tumors (21.7% vs. 5.8%; P < .001). Second primary cancer diagnosis was more frequent in BRCA1 compared with BRCA2 mutation carriers (36.2% vs. 10.7%; P < .001), whereas there was no difference in 15-year overall survival (hazard ratio, 0.92; 95% confidence interval, 0.48-1.83; P = .804) between the 2 groups. CONCLUSIONS: These data confirm established observations in the pathology of BRCA-related tumors and provide further insight on the association of rare histologic entities with mutations in these genes, which can be clinically beneficial.

Germline deleterious mutations in genes other than BRCA2 are infrequent in male breast cancer.

PURPOSE: Male breast cancer (MBC) is a rare cancer entity, with mutations in BRCA1 and BRCA2 genes accounting for ~ 10% of patients. Multiple-gene sequencing has already entered clinical practice for female breast cancer, whereas the performance of panel testing in MBC has not been studied extensively. Therefore, the aim of this study was to evaluate the clinical utility of panel testing for MBC, by the largest gene panel used so far, through investigation of patients deriving from a population with known founder effects. METHODS: Genomic DNA from one hundred and two Greek MBC patients, unselected for age and family history, was used to prepare libraries which capture the entire coding regions of 94 cancer genes. RESULTS: Loss-of-function (LoF) mutations were found in 12.7% of the cases, distributed in six genes: BRCA2, ATM, BRCA1, CHEK2, PMS2, and FANCL. BRCA2 mutations were the most frequent, followed by ATM mutations, accounting for 6.9 and 2%, respectively, while mutations in other genes were detected in single cases. Age at diagnosis or family history was not predictive of mutation status. Beyond mutations in established breast cancer predisposing genes, LoF mutations in PMS2 and FANCL among MBC patients are reported here for the first time. CONCLUSIONS: Our findings, using the largest gene panel for MBC patients so far, indicate that BRCA testing should be the primary concern for MBC patients. Until sufficient evidence arises from larger studies, multiple-gene panels may be of limited benefit for MBC and their families, at least for MBC patients of specific descent.