Red and processed meat intake and cancer risk: Results from the prospective NutriNet-Santé cohort study

The International Agency for Research on Cancer (WHO-IARC) classified red meat and processed meat as probably carcinogenic and carcinogenic for humans, respectively. These conclusions were mainly based on studies concerning colorectal cancer, but scientific evidence is still limited for other cancer locations. In this study, we investigated the prospective associations between red and processed meat intakes and overall, breast, and prostate cancer risk. This prospective study included 61,476 men and women of the French NutriNet-Santé cohort (2009-2015) aged ≥35 y and who completed at least three 24 hrs dietary records during the first year of follow-up. The risk of developing cancer was compared across sex-specific quintiles of red and processed meat intakes by multivariable Cox models. 1,609 first primary incident cancer cases were diagnosed during follow-up, among which 544 breast cancers and 222 prostate cancers. Red meat intake was associated with increased risk of overall cancers [HR_Q5vs.Q1 =1.31 (1.10-1.55), p_trend  = 0.01) and breast cancer (HR_Q5vs.Q1  = 1.83 (1.33-2.51), p_trend  = 0.002]. The latter association was observed in both premenopausal [HR_Q5vs.Q1 =2.04 (1.03-4.06)] and postmenopausal women [HR_Q5vs.Q1 =1.79 (1.26-2.55)]. No association was observed between red meat intake and prostate cancer risk. Processed meat intake was relatively low in this study (cut-offs for the 5th quintile = 46 g/d in men and 29 g/d in women) and was not associated with overall, breast or prostate cancer risk. This large cohort study suggested that red meat may be involved carcinogenesis at several cancer locations (other than colon-rectum), in particular breast cancer. These results are consistent with mechanistic evidence from experimental studies.