Does Prior Breast-Feeding Improve Breast Cancer Outcomes?

In the U.S., one in eight women will be diagnosed at some point with breast cancer. To explore the effects of lactation history on prognosis of women with various subtypes of breast cancer, researchers followed a cohort of 1636 women for a median of 9 years after completion of treatment. The investigators tested tumors for 55 genes and used algorithms to identify 5 cancer subtypes: luminal A, luminal B, human epidermal growth factor receptor 2 (HER2)-enriched, basal-like, and normal-like breast tumors.

In analyses adjusted for confounders (e.g., age at diagnosis, race, parity, tumor stage, subtype), a history of any lactation was associated with 30% lower risk for recurrence and 28% lower risk for breast cancer death. Among women who had lac…