Despite a lack of evidence, a growing number of women are choosing to remove a healthy breast after being diagnosed with cancer in the other breast, according to a study of nearly 70,000 New York women who had mastectomies. Overall, some 6,300 women (9 percent) opted for a mastectomy for preventive (prophylactic) reasons.

The numbers were low at the beginning -- fewer than 300 diagnosed with breast cancer opted for this treatment in 1995 -- but more than doubled by the end of the 11-year study in 2005 to nearly 700.

Preventive mastectomies aren't a panacea, however. For one, removing the second breast may be considered preventive, but there's no evidence that removing an unaffected breast improves a woman's long-term survival, according to researchers. And, for women who don't have an elevated genetic risk of breast cancer, encompassing 95 percent of all breast cancer patients, the odds are very low -- 10-20 percent -- of developing cancer in the second breast over a generation. Plus, there may be complications, including nerve damage, bleeding and infection.

Cancer September 28, 2009

MSNBC September 28, 2009

EurekAlert September 28, 2009