The survey conducted by Dana-Farber Cancer Institute investigators also showed that many patients opt for the procedure, known as a contralateral prophylactic mastectomy, or CPM, despite knowing it will be unlikely to improve their chance of survival.
According to the authors, the study showed a certain disconnect between what many patients know on an abstract, intellectual level- that CPM has little impact on survival rates for most women- and the choices they make after receiving the anxiety-inducing diagnosis of breast cancer.
In the survey, researchers canvassed 123 women age 40 or younger who had undergone a bilateral mastectomy despite having cancer in only one breast.
Almost all the women said they opted for CPM out of a desire to improve their chances of survival and prevent the cancer from spreading to other parts of the body.
"Most women acknowledge that CPM does not improve survival, but anxiety and fear of recurrence probably influence them during the decision-making process," study's lead author Shoshana Rosenberg, ScD, MPH, of the Susan F. Smith Center for Women's Cancers at Dana-Farber Rosenberg.
The survey also indicated that women who don't inherit an increased genetic risk of breast cancer tend to overestimate the chance that cancer will develop in both breasts, where as respondents who did have an inherited predisposition to breast cancer more accurately perceived their risk for cancer in both breasts.
Even as they overestimated the benefits of CPM, many of the participants underestimated the severity of some of its side effects.
The study is published in Annals of Internal Medicine.