MRI most effective for detecting breast cancer for women with breast cancer gene mutations

MRI is more accurate for detecting breast cancer than mammography, ultrasound or clinical breast examination alone, in women who carry the BRCA1 or BRCA2 gene mutation, according to a study in the September 15 issue of JAMA.

Women with BRCA1 and BRCA2 mutations who do not undergo prophylactic surgery have a lifetime risk of breast cancer of up to 85 percent, with a significantly higher risk of breast cancer than the general population from age 25 years onward, according to background information in the article. Current recommendations for women who have a BRCA1 or BRCA2 mutation are to undergo breast surveillance from age 25 years onward with mammography annually and clinical breast examination (CBE) every 6 months; however, many tumors are detected at a relatively advanced stage. Magnetic resonance imaging (MRI) and ultrasound may improve the ability to detect breast cancer at an early stage.

Ellen Warner, M.D., of Toronto-Sunnybrook Regional Cancer Centre, Toronto, Ontario, Canada, and colleagues compared the sensitivity and specificity of four methods of breast cancer surveillance (mammography, ultrasound, MRI, and CBE) in women with hereditary susceptibility to breast cancer due to a BRCA1 or BRCA2 mutation.

The study included 236 women aged 25 to 65 years with BRCA1 or BRCA2 mutations who underwent 1 to 3 annual screening examinations, consisting of MRI, mammography, and ultrasound at a teaching hospital between November 1997 and March 2003. On the day of imaging and at 6-month intervals, CBE was performed.

During the study period, there were 22 cancers detected (16 invasive and 6 ductal carcinoma in situ). Of these, 17 (77 percent) were detected by MRI vs. 8 (36 percent) by mammography, 7 (33 percent) by ultrasound, and 2 (9.1 percent) by CBE. All 4 screening modalities combined had a sensitivity of 95 percent vs. 45 percent for mammography and CBE combined.

“This study of 236 BRCA1 and BRCA2 mutation carriers demonstrates that the addition of annual MRI and ultrasound to mammography and CBE significantly improves the sensitivity of surveillance for detecting early breast cancers,” the authors write. “… 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, but it is necessary to demonstrate that this surveillance tool lowers breast cancer mortality before it can be recommended for general use.”