Breast-Feeding Might Cut Risk for Tough-to-Treat Breast Cancer: Study

Researchers found association between time spent nursing and risk of hormone-negative tumors

THURSDAY, Oct. 18 (HealthDay News) -- Breast-feeding may reduce a woman's risk for a form of breast cancer that's particularly difficult to treat, a new study suggests.

The study, by researchers at Columbia University, found that breast-feeding lowered the odds for estrogen receptor-negative and progesterone receptor-negative (ER/PR-) breast cancer.

These types of tumors have cells that do not carry a protein on their surface that binds to the hormones estrogen or progesterone. This means that they cannot be treated with standard hormone-based therapies.

Since there are few modifiable factors for ER/PR-negative breast cancers, the researchers concluded that women at risk for this type of tumor should be encouraged to breast-feed.

The study is scheduled to be presented Thursday at the annual cancer prevention conference of the American Association for Cancer Research (AACR) in Anaheim, Calif.

"We found an increased risk for estrogen receptor- and progesterone receptor-negative breast cancer in women who do not breast-feed, but in women who have children and breast-feed, there is no increased risk," study co-author Meghan Work, a doctoral student in the department of epidemiology at Columbia's Mailman School of Public Health in New York City, said in an AACR news release.

Still, one expert said the findings must be interpreted with caution.

"This was an observational study, and a causal relationship between breast-feeding and the decreased incidence of hormone-negative breast cancer is not established," stressed Dr. Alyssa Gillego, from the department of breast surgical oncology at Beth Israel Comprehensive Cancer Center, in New York City.