BRCA 1–2 Incidence in Synchronous and Metachronous Breast Cancer: a Tertiary Center Study

The incidence of synchronous or metachronous bilateral breast cancer (SBBC vs. MBBC) has been reported to range from 1.4 to 11.8%. BRCA1/2 deleterious mutation is a significant risk factor for developing synchronous or metachronous bilateral breast cancer. We aimed to examine the clinical and pathological results of patients who developed synchronous or metachronous bilateral breast cancer and to whom we applied BRCA1/2 tests. The files of 1420 patients with breast cancer were analyzed. Among 33 breast cancer patients who underwent the BRCA1/2 gene test, 16 synchronous and 17 metachronous bilateral breast cancer patients were included. Demographics, family history, preoperative diagnosis, tumor properties, histopathological results, immunohistochemistry, multicentrity, stages, metastasis status, mastectomy applications, local and axillary recurrence status, neoadjuvant chemotherapy (NCT), adjuvant therapy age at the first and second tumor, the time elapsed between the development of two tumors, the differences between the synchronous or metachronous tumors, BRCA testing results, overall survival, and disease-free survival were analyzed retrospectively. BRCA 1/2 gene was positive in 8/16 SBBC and 8/17 MBBC. Ten patients were identified as BRCA1 + and six patients as BRCA2 + . BRCA1/2 + two patients and BRCA1/2- two patients died due to metastatic disease. Survival time did not differ significantly between SBBC and MBBC groups (p = 0.153). The survival curves of the patients with or without the BRCA1/2 deleterious mutation did not differ significantly, and the BRCA1/2 variant did not significantly affect survival (p = 0.957). Patients with synchronous or metachronous bilateral breast cancer are likely to be carriers of the BRCA1/2 deleterious mutation. If the BRCA1/2 mutation is investigated and detected in suitable patients, effective methods can be developed to screen other cancer types that may occur alongside breast cancer in these patients, and morbidity and mortality rates can be reduced.