When breast cancer strikes, patients can opt to have their healthy breast removed even though the chance of recurrence is extremely low. But according to a new study, published in the journal Annals of Surgery, that isn’t stopping patients from doing it anyway. A team of researchers found the number of double mastectomies performed in the United States has tripled over the last 10 years.

"Despite all the data comparing women who underwent breast-conserving surgery and mastectomy and the survival was exactly the same, the rate of bilateral mastectomy is actually picking up and not slowing down," said the study’s lead researcher Dr. Mehra Golshan, distinguished chair in surgical oncology at Brigham and Women's Hospital.

According to the American Cancer Association, a mastectomy is a surgical procedure that involves removing all of the patient's breast tissue, typically to remove cancerous tissue as a preventive measure against cancerous growth. There are several different types of mastectomy surgeries, but the most common is as the total removal of one or both breasts. Some patients elect to undergo the surgery for both breasts in order to reduce the risk of developing breast cancer in the first place.

The procedure, known as a contralateral prophylactic mastectomy (CPM), can help reduce risk in women who have mutations in the genes BRCA 1 and BRCA 2 genes. However, it’s likely that undergoing the breast removal surgery is an unnecessary preventive measure for those without the genetic mutations.

For the study, Golshan and her research team analyzed data collected from 2002 to 2012 using the Surveillance, Epidemiology, and End Results (SEER) database — a national cancer registry including nearly 500,000 women. All of the participants had stage one, two, or three breast cancer occurring in one breast. Most of the women (59.6 percent) underwent a lumpectomy, in which they undergo surgery to remove a small portion of the cancerous tumor or tissue lump. Another 33.4 percent of women underwent a mastectomy to remove the unhealthy breast.

Researchers noticed the number of women opting for CMP increased from 3.9 percent in 2002 to 12.7 percent in 2012. And yet, with less than one percent of breast cancer survivors experiencing disease recurrence in their unaffected breast later on in life, researchers aren't sure this is necessary.

The rates of preventive breast removal surgeries may be driven, at least in part, by the fact some insurance companies cover surgical options women may potentially choose from, including lumpectomy to single or double mastectomy. However, there is no federal law requiring insurance provides to cover prophylactic mastectomies — coverage ultimately varies state by state.

"What we saw is that the rates of prophylactic mastectomy is not only increasing, but increasing more quickly," Golshan said. "Whether it’s patient perception, what the doctors tells the patients, how we discuss the options — we’ve got to figure out what is driving prophylactic mastectomy rates so high. Removing the opposite, happy, healthy breast in general for most women diagnosed with breast cancer doesn’t make sense."

Source: Golshan M, Wong SM, Freedman RA, Sagara Y, Aydogan F, and Barry WT. Growing Use of Contralateral Prophylactic Mastectomy Despite no Improvement in Long-term Survival for Invasive Breast Cancer. Annals of Surgery. 2016.