Women who inherit mutations in the BRCA1 or BRCA2 cancer susceptibility genes have a 45 percent to 65 percent lifetime risk of developing breast cancer, according to background information in the article. The risk can be reduced by prophylactic mastectomy but many BRCA1/2 mutation carriers choose instead to seek effective screening strategies that detect breast cancer early. Screening with contrast-enhanced breast magnetic resonance imaging (MRI) has been shown to detect disease earlier than mammography in high-risk women; cancers detected by MRI are often axillary (near the armpit) lymph-node negative and stage I. Although breast MRI screening is highly sensitive, it increases the rate of false-positive test results, and it has not been shown to reduce the death rate from breast cancer. Additionally, breast MRI screening is at least 10 times more expensive than mammographic screening and generates higher diagnostic costs. Because cost may be the greatest barrier to broader evaluation and dissemination of breast MRI screening, its cost-effectiveness is a critical consideration.
Sylvia K. Plevritis, Ph.D., of Stanford University School of Medicine, Stanford, Calif., and colleagues evaluated the cost-effectiveness of adding breast MRI screening in BRCA1/2 mutation carriers. A computer model was used that simulates the life histories of individual BRCA1/2 mutation carriers, incorporating the effects of mammographic and MRI screening. The accuracy of mammography and breast MRI was estimated from published data in high-risk women. Breast cancer survival in the absence of screening was based on the Surveillance, Epidemiology and End Results database of breast cancer patients diagnosed in the prescreening period (1975-1981), adjusted for the current use of supplemental therapy. Utilization rates and costs of diagnostic and treatment interventions were based on a combination of published literature and Medicare payments for 2005.
"At a cost-effectiveness threshold of $100,000 per quality-adjusted life-year gained, adding annual MRI from ages 35 to 54 years is cost-effective among all BRCA1 mutation carriers and among BRCA2 mutation carriers for whom mammography is insensitive. Magnetic resonance imaging has a larger role in screening BRCA1 mutation carriers because they are at greater risk for developing breast cancer and their cancers are more aggressive than those that develop in BRCA2 mutation carriers," the authors write.
The researchers add that screening with MRI becomes more cost-effective as the breast cancer risk increases, mammography performance worsens, greater quality of life gains accrue from MRI and the cost of MRI decreases.
"With substantial declines in its cost, breast MRI screening is likely to represent an acceptable value for a broader group of women."
(JAMA. 2006;295:2374-2384. Available pre-embargo to the media at www.jamamedia.org)
Editor's Note: : This study was funded by National Institutes of Health grants and by a California Breast Cancer Research Program Fellowship Award.
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