Findings published today in the Journal of the American Medical Association suggest that for some women, the best tool for finding breast cancer early may not be a mammogram. The study results indicate that women who have mutations in the so-called breast cancer susceptibility genes (BRCA1 and BRCA2) may be better off getting MRIs.

Having a mutation in either or both BRCA1 and BRCA2 raises a woman's lifetime risk of developing breast cancer significantly. As a result, patients who know they are carrying the genetic mutation are urged to undergo preventive testing every six months. Ellen Warner of the Toronto-Sunnybrook Regional Cancer Center and her colleagues compared four techniques--MRI, mammography, ultrasound and clinical breast exams--utilized by a group of 236 women identified as having breast cancer gene mutations. For six years, the patients received between one and three screenings annually using all of the methods. The team determined that MRIs were the most successful at catching the cancers that developed in the group, doing so 77 percent of the time. In comparison, 36 percent of the cases were detected by mammography and 33 percent by ultrasound.

Our results support the position that MRI-based screening is likely to become the cornerstone of breast cancer surveillance for BRCA1 and BRCA2 mutation carriers, the authors write, but it is necessary to demonstrate that this surveillance tool lowers breast cancer mortality before it can be recommended for general use. In an accompanying commentary, Mark E. Robson and Kenneth Offit of New York's Memorial Sloan-Kettering Cancer Center support the proposal that women with a genetic predisposition to breast cancer should be offered MRI screening. They caution, however, that factors such as equipment level, different imaging protocols and radiologist experience could result in MRI screenings that are less effective than those described in the study.