Breast MRI's role in mastectomies remains open

An editorial published in BMJ has stirred up debate once again about whether breast MRI leads to more mastectomies. The author said yes it does while others insist it does not.

Routine use of breast MRI in managing of patients with early-stage breast cancer may be unwarranted; there is no evidence to support a clear benefit in that setting, according to Malcolm Kell, a consultant surgeon and senior lecturer at Eccles Breast Screening Unit at University College Dublin in Ireland.

Kell references a meta-analysis published in 2008 in the Journal of Clinical Oncology that concluded MR staging identifies additional disease in nearly one in five women previously diagnosed with breast cancer. It also suggests that women may undergo more extensive surgeries than originally planned because of false-positive MR findings.

Results published in The Lancet from a more recent study, the Comparative Effectiveness of Magnetic Resonance Imaging in Breast Cancer (COMICE) trial, also found the rate of mastectomy was higher in the MRI group versus those who did not undergo MRI (7% vs. 1%). COMICE was a multicenter randomized controlled trial conducted in the U.K. to assess the impact of MR mammography in patients with breast cancer who were thought to be amenable to breast-conserving treatment after standard triple assessment.

“MR mammography identifies occult disease in the breast that may not be visible on other imaging modalities, and this may lead to inappropriate treatment decisions,” Kell said.

Clear and consistent evidence from a large number of studies indicate preoperative MRI is directly associated with a change from planned breast conservation to more radical surgery, according to Dr. Nehmat Houssami, coauthor of the Journal of Clinical Oncology study and an associate professor at the University of Sydney in Australia.

Houssami agrees with the editorial and said routine use of preoperative MRI in women newly diagnosed with breast cancer does not improve clinical outcomes and appears to be causing unnecessary mastectomy in women who would have received breast-conserving surgery otherwise.

“The results of COMICE are very important and represent evidence from a randomized controlled trial, hence removing the effect of confounding and bias,” she said. “It would be fair to say that MRI advocates/experts have been critical of the COMICE trial. In my opinion this seems to be a case of shooting the messenger.”

The COMICE study is the only randomized controlled trial to examine reoperation rates in women planning to have breast-conservation surgery and has demonstrated that preoperative MRI does not have a significant effect in reducing reexcision surgery, she said.

“We must be careful not to keep referring to small, nonrandomized studies to counter the evidence provided from a large randomized, controlled trial such as COMICE,” she said.

Not everyone agrees with Kell’s position.

Many studies reveal breast MRI can detect additional lesions when performed in patients just diagnosed with cancer. This will inevitably lead to additional surgery, such as wider lumpectomy or mastectomy, but that doesn’t mean MRI is to blame, according to Dr. Stamatia Destounis, an attending radiologist at Elizabeth Wende Breast Care in Rochester, New York.

“We have found more of our patients choosing mastectomies. However, I believe that is based on patients discussing all options with their surgeons, having genetic testing that is positive, or having several family members with history of cancer,” she said. “I don’t think MRI alone has caused women to choose mastectomy over lumpectomy.”

Plus, additional cancer may be found in the other breast, she said. There is no way of knowing whether the tumor that remains undiagnosed without breast MRI is the one that will affect the patient’s survival.

“MRI should be performed in women with newly diagnosed breast cancer, especially if they are premenopausal, have dense breast tissue that may make the mammogram difficult to interpret, and/or strong family history,” Destounis said. “We make more of a difference when we find the small breast tumors, which are easier to treat and cure.”