African-American women are at higher risk for hormone receptor-negative breast cancer, one of the most difficult subtypes to treat, but this risk could be ameliorated somewhat by breast-feeding their children.

"African-American women are more likely to have had a greater number of full-term births and less likely to have breast-fed their babies," said Julie Palmer, Sc.D., professor of epidemiology at the Slone Epidemiology Center at Boston University. "This study shows a clear link between that and hormone receptor-negative breast cancer."

Palmer based her report, published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, on the Black Women's Health Study, which has followed 59,000 African-American women since 1995.

Between 1995 and 2009, researchers recorded 457 cases of hormone receptor-positive breast cancer and 318 cases of hormone receptor-negative breast cancer among study participants.

For women who had two or more children, there was a 50 percent increased risk of hormone receptor-negative breast cancer. However, among women who breast-fed, there was no longer a significant increased risk.

For estrogen receptor-positive breast cancer, a higher birth rate was associated with a decreased risk and breast-feeding had no effect.

"The adverse effect of high childbirth without subsequent breast-feeding seems to be confined to the hormone receptor-negative breast cancer, which carries a higher mortality rate and is more common in African-Americans," said Palmer.

Source: AACR