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MRIs Recommended for Women with Breast Cancer Gene Mutations

By Cheryl Simon Silver

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Breast Cancer
Personalized Medicine

Women at the highest levels of hereditary risk for breast cancer should be offered magnetic resonance imaging (MRI) breast screening, a new study recommends.

Researchers at Toronto-Sunnybrook Regional Cancer Centre in Toronto, Ontario, studied 236 Canadian women, aged 25 to 65 years, who carry the BRCA1 or BRCA2 mutations. They found that in women with these gene mutations, MRI detects early breast cancers with greater sensitivity than mammography, ultrasound, or clinical breast examinations alone.

Lead researcher Ellen Warner says the MRI yields better results in part because women who carry the gene mutations may develop breast cancer at younger ages than women without the mutations, and younger women tend to have denser breast tissue than older women. Mammography is less successful in revealing tumors dense breast tissue. The shape of BRCA1-related tumors also makes them look more benign in mammograms than they do in MRI.

The 236 Canadian women underwent all four screening methods on the same day. A total of 22 cancers were detected in the women, some by more than one method.

Of these, MRI detected 17 (77 percent) compared to 8 (36 percent) by mammography, 7 (33 percent) by ultrasound, and 2 (9 percent) by clinical examination by a health professional. Two of the tumors were missed by MRI, and found by only by mammography.

“What’s notable is that we found cancers at an early stage,” Warner says. “Less than 10 percent had spread to the lymph nodes—an important indicator of prognosis.” Several years later, all of the women are alive and cancer free, she adds.

She and her colleagues will follow the study participants for five or more years to see if their survival rates are improved over those of BRCA1 and BRCA2 carriers who are not in the study.

Women with a BRCA1 or BRCA2 mutation currently are advised to begin annual mammography and clinical breast examination every six months. Their lifetime risk of breast cancer is as high as 85 percent, and some women who carry the mutations opt for prophylactic breast removal.

If the early detection afforded by MRI screening indeed improves survival, the need for prophylactic mastectomy would diminish, Warner says.

The findings appear in the Journal of the American Medical Association. An accompanying commentary by Mark Robson and Kenneth Offit, both of Memorial Sloan-Kettering Cancer Center, says the study shows that “this new technology provides important new information for women at hereditary risk regarding their surveillance options.”

Warner and colleagues write that “MRI-based screening is likely to become the cornerstone of breast cancer surveillance for BRCA1 and BRCA2 mutations carriers” but refrain from recommending MRI for general screening until it can be shown to reduce breast cancer mortality.

A woman without the gene mutations who has an MRI for routine screening is likely to undergo an unnecessary biopsy, Warner says. “The lower your risk, the lower the chance that you’re going to benefit.”

Warner, E. et al. Surveillance of BRCA1 and BRCA2 Mutation Carriers with Magnetic Resonance Imaging, Ultrasound, Mammography, and Clinical Breast Examination. JAMA 292, 1317-1325 (September 15, 2004).

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