Is MRI causing an unwarranted spike in mastectomies?

By 2006, more than 1 in every 5 women (22%) with breast cancer being treated at the Mayo Clinic received preoperative magnetic resonance imaging (MRI). At the same time, the number of women with breast cancer choosing mastectomy over breast-conserving surgery-which had decreased from 45% in 1997 to 30% in 2003-rebounded to levels of a decade earlier. Women who received preoperative MRI were more likely than those who did not to undergo a mastectomy.

The finding, presented at the annual American Society for Clinical Oncology meeting in May, comes from the first large retrospective study to find a possible association between mastectomy and MRI, underscoring what many practitioners have been reporting anecdotally. The study included approximately 5,500 women with breast cancer who had undergone surgery at the Mayo Clinic between 1997 and 2006.

A previous investigation has shown that while MRI can help diagnose breast cancers missed by mammography and ultrasound imaging, its false-positive rate is 70% to 80%, compared with that for screening mammography of about 10%. As a result, many women are followed with additional imaging studies and biopsies for lesions that are often not cancerous. The tension of a prolonged investigation, as well as false-positive findings, make a number of these women choose mastectomy.

Hede K. Possible MRI-mastectomy link sparks debate on MRI's role in breast cancer management. J Natl Cancer Inst. 2008;100:1052-1054.Katipamula R, Hoskin TL, Boughey JC, et al. Trends in mastectomy rates at the Mayo Clinic Rochester: Effect of surgical year and preoperative MRI. J Clin Oncol. 2008;26:(May 20 suppl;Abstr 509).