799 Breast cancer in BRCA1 and BRCA2 mutations carriers, clinicopathological features

Introduction/Background* Mutations in the BRCA1 or BRCA2 susceptibility genes are associated with most hereditary breast cancers with an identified pathogenic variant. These genes are implicated in about 15% of women with familial breast cancer. The aim of this study is to evaluate clinicopathological features of breast cancer diagnosed in BRCA1/2 mutations carriers. Methodology A retrospective descriptive study of all women diagnosed with BRCA gene mutations at a high-volume center between January 2007 and October 2020 was performed. Patients‘ history of breast and ovarian cancer was collected. IBM SPSS Statistics® v25.0 was used for statistical analyses. Result(s)* We included 165 patients diagnosed with BRCA1 and BRCA2 mutation, of which 91 women were diagnosed with breast cancer (58.8% among BRCA1 carriers and 51.8% among BRCA2 carriers). The mean age at diagnosis was 41.4 (SD 9.6) and 42.7 (SD 10.5) years for BRCA1 and BRCA2 respectively (p=0.54). In 32 women, risk-reducing mastectomy (RRM) was performed without previous diagnosis of breast cancer. In 87%, the histological type was infiltrating ductal carcinoma (IDC), and the most frequent intrinsic subtypes were, for BRCA1, pure-HER2 (70%), luminal B (11%) and triple-negative (6.8%), and for BRCA 2, Luminal HER2 (39%), Luminal B (25%) and pure-HER2 (19.4%). No differences in stage at diagnosis were found between patients with BRCA1 and BRCA2 (p=0.073) with 39.4% and 36.7% of cases of lymph node involvement respectively (p= 0.701). Chemotherapy was used as primary treatment in 32% of patients with an anatomopathologic complete pathologic response rate in 47% of cases. The response to chemotherapy was similar in both types of germline mutation (p= 0.722). Conclusion* To be a BRCA mutation carrier is associated with an increased risk of breast cancer at earlier ages than the general population, with no significant differences between the two types of mutation. The most frequent intrinsic subtype was different between the two groups while the stage at diagnosis was similar.