Contralateral breast cancer in patients carrying mutations in the BRCA1∕2 gene.

Aim: This study aim was to offer a better view of breast cancer (BC) in Romanian patients and to identify the most frequent BRCA1∕2 germline mutations in a cohort of Romanian patients with contralateral BC (CBC). This is one of the first comprehensive studies to determine the contribution of BRCA1∕2 germline mutations to CBC development in the Romanian population.

Patients, materials and methods: This is a prospective study and included 281 patients with BC. We established the histological type and immunohistochemical profile for these breast tumors. We identified mutations in the BRCA1∕2 oncogenes in those patients diagnosed with CBC. We investigated correlations between the BRCA1∕BRCA2 genes mutation and the increased risk of collateral BC.

Results: The most common histological type observed was ductal carcinoma. Our study group of tumors was classified into the following BC subtypes: 84.69% triple-negative BC, 9.60% Luminal A, 3.55% human epidermal growth factor receptor 2 (HER2)-positive and 2.13% Luminal B. Forty-one cases were diagnosed with collateral BC. For these 41 cases, genetic testing was performed for the BRCA1 and BRCA2 genes and we obtained seven cases with negative results and 34 cases with positive results for mutations in the BRCA1 gene, describing the following types of mutations: c.3067.C>T (24 cases - 70.6%), c.5266dupC (four cases - 11.8%), c.4035delA (six cases - 17.6%).

Conclusions: This study offered a better view of BC in Romanian patients and identified the most frequent BRCA1∕2 germline mutations in a cohort of Romanian patients with CBC. Also, these results demonstrate that BRCA1 gene mutations increase the risk for CBC development.