According to a new study published in the Journal of the National Cancer Institute, African American women who have had children and breastfeed have a decreased risk for developing estrogen receptor–negative breast cancer and triple-negative breast cancer compared with women who did not breastfeed.
In the study, researchers from Boston University in Boston, Massachusetts, the Roswell Park Cancer Institute in Buffalo, New York, and the University of North Carolina in Chapel Hill, North Carolina, analyzed data from 3,698 African American women with breast cancer, 1,252 of which had estrogen receptor–negative breast cancer.
The researchers found that women who have had children had a 33% increased risk for developing estrogen receptor–negative breast cancer compared with women who did not have children. Furthermore, women who had given birth at least four times and never breastfed had a 68% increased risk for developing estrogen receptor–negative breast cancer compared with women who gave birth once and breastfed. In addition, the risk for developing estrogen receptor–positive breast cancer was slightly reduced in women who gave birth at least four times.
Researchers suggest that breastfeeding may prevent some cases of estrogen receptor–negative breast cancer in African American women.
Women who have had children (parous women) appear to have an increased risk of developing estrogen receptor-negative breast cancer, the subtype that carries a higher mortality rate and is more common in women of African ancestry.
A similar relationship was found for triple-negative breast cancer. However, the association between childbearing and increased risk of estrogen receptor-negative and triple-negative breast cancer was largely confined to the women who had never breastfed. These findings, published in the Journal of the National Cancer Institute, suggest that low rates of breastfeeding in African American women may contribute to their higher incidence of the more aggressive and difficult-to-treat subtypes of breast cancer.