A new study by Canadian researchers shows that some women with real or perceived genetic risks for breast cancer and who opt to have their breasts removed as a preventative measure may have an exaggerated idea of their true cancer risks. Researchers at the University of Toronto interviewed 75 women who had undergone breast removal to prevent cancer and found that the women's estimates of their chances of getting the disease were "statistically significantly overestimated" by all but a few who did have a genetic predisposition for the disease. The full study appears in the October 16 edition of the Journal of the National Cancer Institute.
On average, the researchers found, the women estimated before surgery that their chance of developing cancer was about 76%. But a computer assessment for 61 of the women put their pre-surgery cancer risk at only 17% because they were determined to be free of genetic mutations that convey a high cancer risk. For 14 of the women who did carry the genetic mutations, the computer estimated their pre-surgery cancer risk to be at 59%.
Researchers Kelly Metcalfe and Steven Narod theorize that many of the women overestimated their cancer risk because of a family history of the disease, but the researchers noted that most of these women had never been screened for the genetic mutations that actually convey the increased risk. They also said that many of the women studied likely suffered from what they dub "cancer worry," based more on perceived risk than actual risk, which led them to opt for the drastic breast-removal surgery. "Formal genetic counseling may have clarified, for all of the women in our study, their actual risks of breast cancer and relieved their cancer worry, which may have led to fewer women undergoing surgery," the researchers concluded.