Apparently the use of breast MRI (magnetic resonance imaging) scans to evaluate cancer after it had previously been diagnosed is not that good after all. Women who receive an MRI after a new diagnosis of breast cancer delay the actual start of treatment and are also more likely to end up with a mastectomy, as opposed to breast-conserving surgery.

A study on approximately 600 breast cancer patients showed that MRI increased the chances ratio for mastectomy, Richard J. Bleicher, M.D., of Fox Chase Cancer Center in Philadelphia, reported at the 2008 Breast Cancer Symposium.

"Breast MRI is used unpredictably and does not avoid positive margins or improve the rate of conversion from mastectomy to breast-conserving therapy," said Dr. Bleicher. "Without evidence that MRI decreases local recurrence after breast-conserving therapy, it should not be a routine part of patient evaluation for breast-conserving therapy."

Getting back to the investigated patients, 130 had MRIs before surgery to remove their tumors, and 27.7 percent of these had a mastectomy. In the non-MRI group, 19.5 percent had a mastectomy. Their conclusion was that women who had got an MRI were 80 percent more likely to get a mastectomy. Bleicher also said that many of the women would have been candidates for a lesser procedure known as a lumpectomy.

Another research conclusion among others included the failure of MRIs to help surgeons decrease positive margins during surgery.

This study was supported by a U.S. Public Health Service grant and by an appropriation from the Commonwealth of Pennsylvania.