Alison M. Stuebe, Walter C. Willett, Fei Xue, Karin B. Michels
Arch Intern Med. 2009;169(15):1364-1371.
Background Findings from observational studies suggest an inverse association between lactation and premenopausal breast cancer risk, but results are inconsistent, and data from large prospective cohort studies are lacking.
Methods We used information from 60 075 parous women participating in the prospective cohort study of the Nurses’ Health Study II from 1997 to 2005. Our primary outcome was incident premenopausal breast cancer.
Conclusion In this large, prospective cohort study of parous premenopausal women, having ever breastfed was inversely associated with incidence of breast cancer among women with a family history of breast cancer.