18. Genetics of breast cancer.

It is well known that breast cancer often occurs in clusters within families. This clustering can be attributed to mutations in the breast cancer susceptibility genes, BRCA1 and BRCA2, in 16% of familial cases. Women with a family history of breast cancer, in whom no mutation is identified, are still at increased risk of developing the disease. This review addresses methods for estimating and stratifying risk of developing breast cancer based on family history. It also indicates how to identify patients likely to carry mutations in BRCA1 or BRCA2 and gives recommendations for intervention for women with a family history of breast cancer.