Management of women with a family history of breast cancer.

Five to ten per cent of breast cancer results from an inherited germ line mutation. The main susceptibility genes are BRCA1 and BRCA2, but others include Cowden's disease, Li Fraumeni syndrome and ataxia-telangiectasia. For those with BRCA1 or BRCA2 mutations the lifetime probability of breast cancer is between 0.40 and 0.73. Genetic testing needs to be offered to young women with breast cancer before considering testing their relatives. The efficacy of surveillance in women with genetic susceptibility has yet to be proved. The value of tamoxifen as a preventive agent in women with genetic susceptibility has yet to be confirmed. Prophylactic bilateral mastectomy will probably reduce the risk of breast cancer but this may not be absolute because of the difficulty of removing all breast tissue. New approaches may enable the selective destruction of mammary epithelium without disturbance to breast architecture.