167P - Clinicopathological characteristics and BRCA1/2 mutation rate in male breast cancer: a retrospective case series by the Hellenic Society of Medical Oncology

Abstract

Due to its rarity, male breast cancer (MBC) remains an inadequately characterized disease. Germline mutations in the BRCA1/2 genes are considered the most significant risk factor for MBC development. We retrospectively analyzed the clinicopathological characteristics, treatment patterns, and the BRCA1/2 germline mutation rate of BC patients (pts) treated from 1995 to 2014. Pts who were still alive were identified and were invited for genetic counseling and testing. The study was coordinated by the University of Crete School of Medicine. A total of 166 pts were identified through their medical records. Median age at diagnosis was 64. Family history of either FBC or ovarian cancer was positive in 19,9% while 9% had a personal history of gynecomastia. Histology was of Ductal Invasive type in 84% of the pts. Node positive locally advanced disease was diagnosed at 30% of pts, while 18% were metastatic at presentation. ER and/or PR-positive, HER2-negative was the predominant subtype (78.4%), followed by triple-positive (18.1%) and only in few pts triple-negative subtype (3.4%). Histologic grade distribution was: gr. I in 5.4%, gr. II in 53.4% and gr III in 41%. All 99 patients who received genetic counselling consented to BRCA1/2 genetic testing. Overall BRCA1/2 deleterious mutation rate was 6 % (5% BRCA2 and 1% BRCA1), while 3 pts (3%) carried a VUS. Most pts (80%) underwent modified radical mastectomy, 41% of which received adjuvant radiotherapy. Adjuvant systemic therapy was administered to 71.6% (10% had chemotherapy only, 27% hormonotherapy only and 63% both). Metastatic disease was treated with at least 1 line of systemic therapy in 31.9% of pts (chemotherapy in 60% of them), 60% of which proceeded to subsequent lines. In one of the largest national cohorts of MBC pts reported yet, we confirmed similar biological patterns to post-menopausal FBC. BRCA1/2 germline mutation rate is comparable to other European populations. Male Breast Cancer Working Group of the Hellenic Society of Medical Oncology Koumarianou A., Bournakis E., Boutis A., Diamantopoulos N., Katsaounis P., Korantzis I., Lianos E., Tsoukalas N., Bakogeorgos M., Kalampaliki T.