Possible MRI-Mastectomy Link Sparks Debate on MRI's Role in Breast Cancer Management
Authors: K. Hede
Journal: JNCI Journal of the National Cancer Institute (2008)

A fter years of decline, the number of breast cancer patients choosing mastectomy over breast-conserving surgery is on the rise, and a new study suggests that the use of highly sensitive magnetic resonance imaging (MRI) may be at least partly responsible. The study raises questions about the appropriate use of MRI in making treatment decisions about breast cancer and whether the technology should be offered to early-stage, low-risk breast cancer patients. “Sometimes our technologies get ahead of our evidence-based medicine,” said Matthew Goetz , M.D., a medical on cologist at the Mayo Clinic and lead investigator of the study, which looked at surgical outcomes of all earlystage breast cancer patients seen at Mayo Clinic’s Rochester, Minn., hospital from 1997 to 2006. In the retrospective study, presented at the American Society for Clinical Oncology meeting in May, the research team found an association between mastectomy rates and preoperative MRI. The researchers controlled for age, cancer stage at diagnosis, and other confounding variables. Among breast cancer patients at the Mayo Clinic, mastectomy rates declined from 47% in 1997 to 30% in 2003, when only 11% of women received an MRI. By 2006, MRI use had doubled to 22% and the number of women having a mastectomy had returned to its mid-1990s level. The study is the fi rst large retrospective study to fi nd a possible association between mastectomy rates and use of MRI over several years, and it supports what many doctors have noted anecdotally in their own practices. Goetz said that he and his colleagues undertook the study in response to a general sense that more women were undergoing mastectomy in recent years, after yearly declines in the late 1990s. Goetz attributed those declines to a series of studies culminating in a 1990 National Institutes of Health consensus statement that concluded that women with early-stage breast cancer survive as well with breast-conserving surgery and adjuvant radiation as with mastectomy. At the same time, patient advocacy groups lobbied legislators to ensure that surgeons in form breast cancer patients about their surgical options, and laws requiring full disclosure of surgical options were enacted in many states, pressuring doctors to reduce mastectomy rates (JNCI 1994;86: 1202 – 8). However in recent years, breast cancer surgeons have begun using imaging techniques such as ultrasound and MRI to assist in surgical planning. Although the Mayo study did not include information on whether MRI infl uenced women’s decisions for or against having a mastectomy, the study highlights a potentially serious problem associated with increasing use of routine MRI. This technique creates a meticulous image of soft tissue that can help diagnose breast cancers missed by mammography and ultrasound imaging, but it is also associated with a false-positive rate of 70% – 80%. By contrast, the falsepositive rate for screening mammography is about 10%. Other conditions, such as fi broadenomas and fi brocystic changes, can masquerade as cancer in an MRI image. Because of the technique’s low specifi city, patients end up requiring further imaging or biopsies for lesions that are probably not cancer. “I wonder whether patients reach a threshold where they are unwilling to deal with the uncertainty of future imaging and biopsies,” Goetz said. “They are tired of a physician saying, ‘We’re not sure, follow up in 6 months with a repeat test, ’ and so those patients may say, ‘Thank you very much, but let’s just proceed with a mastectomy. ’ ” Surgeons are seeing suspicious lesions with MRI that were not visible before, and once those lesions come to light they demand some kind of action, said Richard Bleicher , M.D., a surgical oncologist at Fox Chase Cancer Center in Philadelphia and lead author of a recent review of the use of MRI in breast cancer management. “But to say that we should be doing MRI in these patients to fi nd the 10% – 30% of women who have foci that we didn’t know about before sort of fl ies in the face of the fact that we were equally successful with breast conservation before we knew about them.” From his review, which appeared in the November 2007 issue of Oncology, Bleicher concluded that MRI does not have a proven benefi t for routine selection of breast conservation. Because the rate of local recurrence of breast cancer is already low, he said, the benefi t of routine MRI use does not outweigh the risk of unnecessary additional surgery. To show that many breast cancers detected by MRI may never have become clinically relevant, Bleicher compared the 5-year rate of breast cancer incidence reported in the SEER (Surveillance, Epidemiology, and End Results) registry with the 1-year incidence rate reported by Constance Lehman, M.D., Ph.D., and her colleagues in a New “I wonder whether patients reach a threshold where they are unwilling to deal with the uncertainty of future imaging and biopsies.”