Breast-Feeding and Breast Cancer

A recent study in the Archives of Internal Medicine raises the possibility (but does not entirely prove) that breast-feeding may lower the risk of breast cancer among women at high risk for the disease. The study gathered data from over 60,000 women who had reported at least one pregnancy by 1997. Among women with close relatives who developed breast cancer, those who breast-fed for a period of time had only 41% as many breast cancers by 2005 as women who had never breast-fed. The lowered cancer incidence was only seen among women at high risk for breast cancer; women with no family history of breast cancer did not benefit from breast-feeding.

Why doesn’t this study prove once and for all that “breast-feeding prevents cancer”? Because it only shows an association between breast-feeding and lowered cancer risk - cause-and-effect has not been proved. Perhaps women who choose to breast-feed are more health-conscious overall. Perhaps they exercise more or have a better diet, and that’s actually what lowered the cancer risk. Further research will be needed to tease out the details.