Developments in the study of familial breast cancer

About 5% of breast cancer may be caused by dominant susceptibility genes, which can be inherited. This would equate to 1250 cases per year in the UK and 9000 in the USA. Even within these cases, there is genetic heterogeneity, meaning there are several genes involved, each giving rise to different patterns of other cancers associated with the familial breast cancer. The identification of these genes will enable the entity of familial breast cancer to be more precisely defined and has implications for management of these breast cancer patients, and their at-risk relatives. The problem with this new area of cancer genetics is that the identification of gene carriers may become possible, and this raises ethical and social issues.