According to a study published in Cancer Epidemiology, Biomarkers & Prevention, African-American women who breastfeed have a reduced risk of getting the aggressive breast cancer ER-negative.
ER-negative (estrogen receptor-negative) is considerably less common than ER-positive, the most common type of breast cancer.
The team, led by Julie R. Palmer, ScD, from Boston University, determined that African-American women who had multiple children and did not breastfeed were 1.5 times more likely to get ER-negative than women with no children.
The team followed the histories of 59,000 African-American women that participated in the Black Women’s Health Study from 1995 until 2009. Participants completed detailed questionnaires at the outset of the study regarding their childbirth and breastfeeding experiences and if they had any history of cancer.
Participants then filled out additional questionnaires every two years detailing any new cancer diagnoses they received.
Of the study participants, 457 women were diagnosed with ER-positive, 318 with ER-negative. Those diagnosed with ER-positive followed known trends with those having more children being at lower risk. Breastfeeding had no effect. ER-negative was the opposite: having more children increased the risk in women who did not breastfeed, but for those who breastfed, the risk was reduced.
This study offers another reason that should encourage new mothers to breastfeed.