BRCA1 and breast cancer: The most common indication for risk‐reducing bilateral NSM for patients in this series was mutation in a breast cancer‐associated gene (104 patients, 76·5 per cent): BRCA1, 62 (45·6 per cent); BRCA2, 35 (25·7 per cent); PTEN, two (1·5 per cent); TP53, three (2·2 per cent); and ATM, two (1·5 per cent) (Table 1).