Contralateral breast cancer and tumor recurrence in BRCA1/2 carriers and non-carriers at a high risk of hereditary breast cancer after bilateral mastectomy.

Contralateral prophylactic mastectomy (CPM) has been reported to reduce risk of contralateral breast cancer (CBC) by at least 90%.In addition, BRCA carriers presents higher risk of ipsilateral recurrence and a second primary tumor. The aim is to evaluate risk of CBC and recurrence and to analyze predictive factors in BRCA1/2 mutation carriers and non-carriers at high-risk of hereditary breast cancer patients. Retrospective observational study. 46 patients underwent bilateral mastectomy during 2004-2018. Cohort comprised 9 patients BRCA1,12 BRCA2 and 25 at high-risk without mutation. Median follow-up 79 months. 16 patients recently diagnosed and 30 previously treated by breast cancer whom underwent CPM at second time (because of later detection of BRCA mutation in 10 cases). The external lateral incision was most frequent surgical technique. In all patients immediate reconstruction was performed. In CPM pieces, 4 in situ carcinoma, 3 invasive and 1 atypical hyperplasia were found. The incidence of occult contralateral cancer was 15.2%. Recurrence was observed in 5 patients a media of 21.2 months after surgery. FSD was 83.74 months and OS 84.33 months. Regression models identified BRCA1/2 mutation and high risk without mutation as significant occult tumor predictive factors while tumor size≥2cm was predictive of recurrence. In our series we found a10.8% recurrence despite CPM and 7 patients (15.2%) would have developed a CBC in subsequent years.