Mastectomies on the rise and MRI use may explain part of the trend, say Mayo researchers

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Researchers say the reasons for this increase are unclear. But they have determined that women at Mayo Clinic who underwent diagnostic magnetic resonance imaging (MRI) prior to surgery to treat early-stage breast cancer had a higher rate of mastectomy, compared to women who did not have an MRI.

"We found that if a woman undergoes an MRI before surgery, she is about 10 percent to 15 percent more likely to have a mastectomy, compared to women who did not undergo MRI," says the study's lead author, Rajini Katipamula, M.D., a senior clinical fellow in hematology/oncology.

Results will be presented May 31 at the 44th Annual Meeting of the American Society of Clinical Oncology (ASCO), and are being highlighted in an ASCO press conference on May 15. The study's senior author, Matthew Goetz, M.D., assistant professor of oncology at Mayo Clinic, will participate in that press conference.

Mayo researchers evaluated mastectomy trends by year and by use of preoperative breast MRI among 5,414 women who had surgery for early-stage breast cancer at Mayo Clinic between 1997 and 2006. They found that the mastectomy rate declined from 44 percent in 1997 to 30 percent in 2003, but then had risen to 43 percent in 2006. During this time, the percentage of women who had breast MRI more than doubled, from 11 percent in 2003 to 23 percent in 2006. The mastectomy rate was significantly higher in women who had a presurgical MRI (52 percent) compared to women who did not have the test and chose breast removal (41 percent).

"Our study is the largest to examine the association between MRI and mastectomy rates at a single institution and may reflect national trends," says Dr. Goetz.

Dr. Goetz says that MRI, which easily detects both cancerous and noncancerous breast lesions, may prompt a woman or her physician to choose total breast removal instead of lumpectomy, even though both procedures have long been proven to offer the same survival benefit.

"What we don't know from this study is whether the higher rate of mastectomy observed in our patients undergoing MRI is related to the detection of additional disease, or whether the uncertainty raised by MRI leads to greater anxiety for the patient and physician, thus leading patients and physicians to choose mastectomy over lumpectomy," says Dr. Goetz.

"Although MRI was associated with a higher mastectomy rate, we cannot assume it is a cause-and-effect relationship," says co-author Amy Degnim, M.D., a breast surgeon at Mayo Clinic and an assistant professor of surgery. "More investigation at an individual level is needed to understand better how MRI may impact personal choices for breast cancer surgery."

Dr. Goetz says that, while MRI was associated with an increased mastectomy rate, the mastectomy rates also increased in women who did not undergo MRI, suggesting other factors are playing an important role in the decision-making process of patients and physicians.

"In the past 10 years, we have observed numerous changes in the preoperative management of patients with breast cancer," says Dr. Goetz. "In addition to new imaging modalities such as MRI, more women are familiar with the role of genetics as a risk factor for breast cancer, and some of our patients are undergoing testing. Additionally, there has been improved access to better breast reconstruction methods."

Lumpectomy plus radiation therapy (known as breast conserving therapy [BCT]) has been the standard of care for most women with early-stage disease since 1990. That year, the National Institutes of Health issued a report stating that BCT was as effective as mastectomy for overall survival for most women with stage I or stage II breast cancer. Shortly thereafter, mastectomy rates began to decline. But the data from Mayo Clinic suggest that this trend may be in reversal.

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