Growth of breast MRI runs afoul of guidelines

Breast MRI use grew quickly in the early 2000s before stabilizing in recent years, but questions remain about whether American Cancer Society (ACS) criteria for use are being followed, according to a study published online Nov. 18 in JAMA Internal Medicine.

“Our data suggest that the majority of women who underwent screening breast MRI did not meet the recommended criteria for appropriate use, whereas many who did meet the criteria did not undergo screening breast MRI,” wrote Natasha K. Stout, PhD, of Harvard Medical School and Harvard Pilgrim Health Care Institute in Boston, and colleagues.

Breast MRI is highly sensitive for detecting breast cancer, making it a tool better suited for screening or surveillance in high-risk women since the technology’s low specificity would lead to more false positive results in a low-risk population. High cost and a lack of evidence regarding mortality benefits also suggest limiting its use, added the authors.

The ACS released guidelines in 2007 stating that breast MRI be used as an adjunct screening tool for women with at least a 20 percent lifetime risk of breast cancer because of a strong family history or due to genetic mutations.

To determine whether the women receiving breast MRI actually fit this profile, Stout and colleagues conducted a retrospective cohort study of a New England-based not-for-profit health plan and multispecialty group medical practice. A total of 10,518 women aged 20 years or older were enrolled in the plan for at least one year and also had at least one breast MRI from 2000 to 2011.

Overall breast MRI use increased sharply from 6.5 per 10,000 women in 2000 to 130.7 per 10,000 in 2009, but then stabilized at 104.8 per 10,000 by 2011. Use especially increased among women with a personal or family history of breast cancer. Screening and surveillance accounted for 57.6 percent of breast MRI use by 2011.

Results showed that in the subset of women receiving screening or surveillance MRIs, only 21 percent had evidence of meeting ACS criteria, while only 48.4 percent of the women with documented deleterious genetic mutations received MRI screening.

The authors wrote that as many as 6 percent of all women are estimated to be eligible for screening MRI. All told, of the approximately 250,000 women included in this analysis, only 1.2 percent underwent screening MRI and few of those had claims-documented history of genetic mutation.

“In our study, screening was the fastest growing indication for a breast MRI, but only approximately half of the 372 women with a claims-documented history of genetic mutations had screening breast MRI and of those, half had multiple screening MRIs,” wrote Stout and colleagues. “This pattern suggests that recommendations for screening high-risk women with breast MRI are beginning to be followed in community practice, but the fact that only half of those eligible for screening breast MRI had one suggests that more should be done.”