Double mastectomies have similar survival rates to lumpectomies and single mastectomies, according to research published July 25 in JAMA Oncology.
Researchers from Canada's Women's College Hospital evaluated breast cancer mortality risk among more than 660,000 women with unilateral breast cancer in the U.S. The patients were divided into three cohorts: those treated with a lumpectomy, a unilateral mastectomy or a bilateral mastectomy.
During a 20-year follow-up period, the researchers found that double mastectomies were associated with a reduced risk of contralateral breast cancer — cancer that develops in the opposite breast from the original diagnosis. Bilateral mastectomy procedures did not lead to lower breast cancer mortality rates, though.
The lumpectomy group saw a 8.54% death rate, the unilateral mastectomy cohort recorded 9.07% and the bilateral mastectomy group noted 8.5%.
"What the hell is going on?" Steven Narod, MD, one of the researchers, told The New York Times.
He said double mastectomies make logical sense for cases of cancer in both breasts, but the findings indicate all three treatment options result in similar survival rates.
Smaller studies have found similar results, according to the Times.