Researchers polled 123 young women two years after they chose double mastectomy for breast cancer at age 40 and younger, asking how they made the decision to have the opposite breast removed and how they estimated the cancer risk in the healthy breast.
"Most women who were considered average risk actually overestimated their risk of having contralateral [opposite breast] breast cancer," said study researcher Shoshana Rosenberg, a research fellow at Harvard School of Public Health and Dana-Farber Cancer Institute.
Despite evidence that having the procedure -- called contralateral prophylactic mastectomy -- does not improve survival rates, growing numbers of women treated for early stage breast cancer decide to have it, the study authors said. While about 6 percent of women with early stage cancers had the procedure in the 1990s, now up to one-fourth do.
Rosenberg and her colleagues wanted to look more closely at the patients' decision-making process. The research is published in the Sept. 17 issue of Annals of Internal Medicine.
In the survey, 98 percent of women who opted for contralateral prophylactic mastectomy said they wanted to avoid getting cancer in the opposite breast and 94 percent said they wanted to improve survival, although only 18 percent believed that the procedure actually improved survival.
About one-quarter of the women were genetically at higher risk of cancer, due to having a BRCA gene mutation. Of participants who did not have the gene mutation, patients estimated that 10 percent would get cancer in the opposite breast within five years without the preventive surgery, although the actual risk is about 2 percent to 4 percent over the five years, according to Rosenberg.
"Risk perception is very complex," Rosenberg said. "It could be that their doctor is not communicating it effectively." In addition, this is a very anxiety-provoking time period. "There are lots of decisions to make, and concerns about recurrence," she noted.
"We are not telling women what surgery to have," Rosenberg said. "We want to be sure they are making an informed decision."
Women should talk over the pros and cons with their physicians, she suggested. While 80 percent of the women said they spoke with their doctor about the reasons for having contralateral mastectomy, only 51 percent reported that their doctors talked about reasons not to have the surgery.
The findings echo some previous research, according to Sarah Hawley, an associate professor of internal medicine at the University of Michigan Health System, in Ann Arbor. In her study, presented last year at a medical meeting, Hawley found that nearly 70 percent of women choosing the contralateral prophylactic mastectomy actually had a low risk of developing cancer in the healthy breast.
"Their findings are consistent with ours, in that desire to prevent cancer in the non-affected breast is a big reason patients reported for getting [contralateral prophylactic mastectomy]," Hawley said.
Better communication is needed to be sure women know the risks and benefits, and lack of benefit of getting the preventive surgery, Hawley pointed out. Better strategies to help patients manage anxiety and worry would help, too, she added.
Women choose to have contralateral prophylactic mastectomy for a number of reasons, said Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital, in New York City. She reviewed the findings.
"Although there may be no survival benefit, many women are concerned that they want to move on with their lives and want to reduce the chance of developing a cancer on the opposite breast in the future," Bernik said. They may be trying, understandably, to avoid another round of treatment in the future.
Women need to decide what is right for them, Bernik stated. "It is clear that with breast cancer surgery, one size does not fit all."
To learn more about cancer prevention, visit the American Cancer Society.