While many women undergo contralateral prophylactic mastectomy (CPM) to remove both breasts after a cancer diagnosis, evidence suggests few of these women actually have a significant risk of developing cancer in both breasts.

A new study has shown that removing the unaffected breast after a breast cancer diagnosis has not been proven to increase survival rates, making CPM potentially unnecessary to prevent the spread of the disease.

Study author Sarah T. Hawley, Ph.D., M.P.H., of the University of Michigan Medical School, Ann Arbor, and colleagues conducted a survey of 2,290 women diagnosed with breast cancer. The results were reported to the Detroit and Los Angeles Surveillance, Epidemiology and End Results (SEER) registries between June 2005 and February 2007, then once more between June 2009 and February 2010.

Of the women in the sample, 18.9 percent considered having CPM done, and 7.6 percent actually underwent the procedure. Most of the patients who underwent CPM had no significant genetic risk factors. Among those who underwent CPM, 80 percent said they made the decision to have the procedure to prevent breast cancer in the other breast. The decision to undergo CPM was linked to risk factors including a strong family history of breast cancer, genetic testing, higher level of education and a greater concern about the recurrence of cancer.

“The growing rate of CPM has motivated some surgeons to question whether performing an extensive operation that is not clinically indicated is justified to reduce the fear of disease recurrence,” said Hawley in a statement.

The findings of the study are published online in the journal JAMA Surgery.