Red and processed meat intake and risk of breast cancer: a meta-analysis of prospective studies.

Epidemiological studies regarding the association between red and processed meat intake and the risk of breast cancer have yielded inconsistent results. Therefore, we conducted an updated and comprehensive meta-analysis which included 14 prospective studies to evaluate the association of red and processed meat intake with breast cancer risk. Relevant prospective cohort studies were identified by searching PubMed through October 31, 2014, and by reviewing the reference lists of retrieved articles. Study-specific relative risk (RR) estimates were pooled using a random-effects model. Fourteen prospective studies on red meat (involving 31,552 cases) and 12 prospective studies on processed meat were included in the meta-analysis. The summary RRs (95 % CI) of breast cancer for the highest versus the lowest categories were 1.10 (1.02, 1.19) for red meat, and 1.08 (1.01, 1.15) for processed meat. The estimated summary RRs (95 % CI) were 1.11 (1.05, 1.16) for an increase of 120 g/day of red meat, and 1.09 (1.03, 1.16) for an increase of 50 g/day of processed meat. Our findings indicate that increased intake of red and processed meat is associated with an increased risk of breast cancer. Further research with well-designed cohort or interventional studies is needed to confirm the association.