Rate of mastectomies decreases with adoption of breast tumor margin guidelines, study finds

Surgery after an initial lumpectomy to obtain more widely clear margins is common and can often lead to more-aggressive surgery, like mastectomy, in patients who may not need additional treatment. In a new study, researchers found that since the 2014 publication of margin guidelines that endorsed a minimal negative margin rates of additional surgery after an initial lumpectomy have decreased, leading to an increase in the overall lumpectomy rate and a decrease in the mastectomy rate. The study found the rate of lumpectomy as the definitive surgical procedure rose by 13 percent, accompanied by a decrease in unilateral (to 18 percent from 27 percent) and bilateral (to 16 percent from 21 percent) mastectomies. Surgery after a lumpectomy, both re-excision and mastectomy, declined by 16 percent overall. The study illustrates that guidelines can be an effective, low-cost approach to addressing clinical controversies.

"The shift away from more-aggressive treatment and the adoption of these guidelines is a positive step in the effort to help women choose the best breast surgery options for them," says Dr. Morrow. "We want women to be confident in their cancer surgery and avoid a mastectomy or additional surgery when medically appropriate. This rapid change, observed within two years of the guidelines' dissemination, illustrates the willingness of the surgical community to adopt evidence-based practices that improve outcomes for their patients."

Prior to 2014, between 25 percent and 33 percent of women who received a lumpectomy returned to the operating room to have additional normal tissue removed or to undergo a mastectomy. Of these women, approximately half had negative margins -- defined as no tumor cells at the edge of the lumpectomy specimen. It had been widely thought that increasing the surgical margin would lower the risk of the cancer returning in that breast. The margin guidelines demonstrated that as long as cancer cells were not on the edge of the tissue removed, bigger margins did not improve patient outcomes. The guidelines were issued jointly by two medical organizations in 2014 and recommended against performing a second procedure following a lumpectomy when margins were clear.

"Our goal in issuing these guidelines was to save patients from unnecessary surgery while still minimizing the risk of the cancer returning," says Dr. Morrow. "It is heartening to see that this primary aim has been met. With more time and further adoption of these guidelines, we anticipate seeing a greater decline in the use of additional surgery after a lumpectomy." The rise in mastectomy as a treatment option when not medically necessary has pushed more doctors to research patient decision-making and the role that anxiety plays in their choices. Many women worry about cancer recurrence, and previous research has found that this appears to drive the decision to have a double mastectomy, even though there is no evidence that the procedure improves outcomes. This study demonstrates that the need for a second surgery is a major driver in the decision for some women to undergo a mastectomy and is a benchmark in the efforts to understand ways to safely minimize the use of aggressive surgery.

The study is a result of work done by Dr. Morrow; co-senior author Reshma Jagsi, MD, DPhil, deputy chair and professor of radiation oncology at the University of Michigan Medical School; and researchers at the university's Cancer Surveillance and Outcomes Research Team (CanSORT), led by Steven J. Katz, MD, MPH, professor of medicine and of health management and policy. "The results of our study underscore a sea change in clinician culture, increasingly committed to harnessing precision medicine to reduce the burden of cancer treatment," says Dr. Katz, also a co-senior author on the study. The collaborative work between CanSORT and Dr. Morrow is the result of a National Cancer Institute grant to the University of Michigan.