Breast cancer: the high-risk mutations.

Mutations in the two known BRCA genes account for only 5% to 10% of breast cancer. The genes may play a role in genomic stability; their role in sporadic cancer remains unknown. Hence, genetic testing has created clinical dilemmas. Some pertain to women whose family history suggests inherited risk. Others, including the false reassurance that may be conferred by a negative finding, apply throughout the general population.