Double mastectomies don't increase cancer survival, study suggests

Women with cancer in one breast have the option to have both breasts removed, as a precaution. However, new research finds that these patients are no less likely to die from breast cancer than women who have only the affected breast or the tumor inside it removed.

The recent study looked at data from more than 660,000 women of various ethnicities in a large U.S. cancer registry. The women were 58 years old, on average, and all had been diagnosed with unilateral breast cancer, meaning cancer in one breast.

Following diagnosis, each patient had one of three standard surgical procedures: a lumpectomy, to remove only the tumor in the affected breast; a unilateral mastectomy, to remove one breast; or a bilateral mastectomy, to remove both breasts. Otherwise, the women were matched in terms of the clinical features of their cancers.

Researchers tracked whether the women developed breast cancer in their remaining breast — a condition called contralateral breast cancer — over 20 years. This can also happen in people with double mastectomies because there's a chance some leftover breast tissue or cancer cells may recur on the chest wall. The risk of contralateral breast cancer happening is usually around 0.4% per year following a unilateral breast cancer diagnosis.

Related: 'Bionic breast' could restore sensation for cancer survivors

The team also recorded whether any of the women died from breast cancer during this follow-up period.

Overall, women who'd had a double mastectomy had a statistically significant, lower risk of developing contralateral breast cancer than the other groups (0.7% versus 6.9%). However, there was no statistically significant difference in overall death rates between groups — these were 16.3% for lumpectomies and 16.7% for both types of mastectomy.