By Alexandra Sifferlin
October 5, 2017

Despite having more treatment options, women with cancer in one breast are increasingly choosing to remove both breasts–even though experts say the procedure does not necessarily lead to better outcomes.

A recent study published in JAMA Surgery found that the increase is driven in part by their surgeons. Doctors generally discourage contralateral prophylactic mastectomy–also known as CPM, or the removal of a healthy breast when the other has cancer–for women at an average risk for additional breast cancer. They do recommend it for women at a higher risk, like those with a mutation in the BRCA gene, which greatly increases the risk of getting the disease. Even so, the rate at which women with cancer in one breast chose to remove both increased nearly sixfold from 1998 to 2011, largely among younger women with early-stage unilateral breast cancer and without genetic risk factors–in other words, women who are candidates for less aggressive treatment.

Survival for these women isn’t higher than it is for women who choose less aggressive options like lumpectomy, also called breast-conserving surgery, in which only a portion of the affected breast is removed. A March 2016 study by researchers at the Duke Cancer Institute looked at about 4,000 women who had breast-cancer surgery and found that removing both breasts did not markedly improve a woman’s quality of life.

So why are women choosing the more invasive option more often? There are likely several reasons for what experts are calling a surge in women undergoing CPM–including a woman’s doctor. The study in JAMA Surgery found that surgeons account for 20% of the variation in rates of women removing both breasts.

In the study, researchers surveyed 5,080 women with early-stage breast cancer and an average risk for cancer in the other breast, along with 377 of their surgeons. They found that while the doctors largely agreed on what they would initially recommend–breast-conserving surgery over CPM–there was variability in what was ultimately performed. A woman had only a 4% chance of undergoing CPM if she went to a surgeon who was among those who were the most reluctant to perform the procedure and most favored breast-conserving surgery. But if a woman went to a surgeon who was among those who were the most open to performing CPM and favored breast-conserving surgery the least, the likelihood of getting CPM was 34%.

The most common reason surgeons gave for being willing to perform CPM, even if they were initially reluctant, was “to give patients peace of mind” and “avoid patient conflict”–not to reduce recurrence or improve survival.

“The emotional reactions to cancer frequently prime patients to desire the most aggressive approach,” says study author Dr. Steven Katz, a professor in the School of Public Health at the University of Michigan. “Our results underscore that most surgeons today favor less aggressive approaches to surgery, and it’s challenging for them to communicate with their patients that bigger is not better.”

In previous research, Katz found that a woman’s fear about cancer recurrence or her desire to avoid regret can also lead to a decision between her and her doctor to choose more aggressive surgery.

Since there is variability in what doctors ultimately agree to perform, women may want to consider visiting more than one doctor before deciding on a treatment plan, Katz says. His research shows that 95% of breast-cancer patients are treated by the first physician they see. “If a patient is not totally in line with what’s being recommended, get a second opinion,” he says.

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This appears in the October 16, 2017 issue of TIME.

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