Association between meat consumption and risk of breast cancer: Findings from the Sister Study.

Meat consumption has been postulated to increase the risk of breast cancer, but this association has not been consistently seen. We examined the association between consumption of different types of meat, meat mutagens and incident invasive breast cancer. Information on consumption of different meat categories and meat cooking practice behaviors was obtained from 42,012 Sister Study participants who completed a Block 1998 Food Frequency Questionnaire at enrollment (2003-2009) and satisfied eligibility criteria. Exposure to meat type and meat mutagens was calculated, and associations with invasive breast cancer risk were estimated using multivariable Cox proportional hazards regression. During follow-up (mean, 7.6 years), 1,536 invasive breast cancers were diagnosed at least 1 year after enrollment. Increasing consumption of red meat was associated with increased risk of invasive breast cancer (HRhighest vs. lowest quartile :1.23, 95% CI: 1.02-1.48, ptrend = 0.01). Conversely, increasing consumption of poultry was associated with decreased invasive breast cancer risk (HR highest vs. lowest quartile : 0.85; 95% CI: 0.72-1.00; ptrend = 0.03). In a substitution model with combined red meat and poultry consumption held constant, substituting poultry for red meat was associated with decreased invasive breast cancer risk (HR highest vs. lowest quartile of poultry consumption: 0.72, 95% CI: 0.58-0.89). No associations were observed for cooking practices, estimated heterocyclic amines or heme iron from red meat consumption with breast cancer risk. Red meat consumption may increase the risk of invasive breast cancer, whereas poultry consumption may be associated with reduced risk. Substituting poultry for red meat could reduce breast cancer risk.