Screening of women at high risk for breast cancer.

A woman may be at high risk of breast cancer because of a strong family history of breast cancer or because she carries a mutation in the BRCA1 or BRCA2 gene. The annual risk for women in this category is between 1% and 2% and the lifetime risk of breast cancer among gene carriers may approach 80%. Several recent trials have reported that the sensitivity of MRI for imaging breast cancer greatly exceeds that of conventional mammography, but no study has yet determined that annual MRI reduces breast cancer-specific mortality. Women with breast cancer and a BRCA1 mutation typically develop aggressive breast cancers and the prognosis is relatively poor for women with small node-negative breast cancers (compared to non-carriers) in particular, if chemotherapy is not given. It is hoped that annual MRI screening combined with appropriate treatment will result in decreased mortality for this and other groups of high-risk women. MRI-based screening for women at moderate risk is a topic of great interest--MRI has not yet been endorsed in moderate risk women because of the high cost of screening and because the specificity of the screening test is not yet determined in this subgroup.