Dietary calcium, phosphorus, vitamin D, dairy products and the risk of colorectal adenoma and cancer among French women of the E3N‐EPIC prospective study

A protective effect of calcium and/or dairy products on colorectal cancer has been reported in epidemiological studies but the findings are considered inconsistent. In particular, it is unclear whether they act at a particular step of the adenoma‐carcinoma sequence. To investigate the effect of dairy product consumption and dietary calcium, vitamin D and phosphorus intake on the adenoma‐carcinoma sequence in the French E3N‐EPIC prospective study. The population for the study of risk factors for adenomas was composed of 516 adenoma cases, including 175 high‐risk adenomas, and of 4,804 polyp‐free subjects confirmed by colonoscopy. The population for the colorectal cancer study was composed of 172 cases and 67,312 cancer‐free subjects. Diet was assessed using a self‐administered questionnaire completed at baseline. There was a trend of decreasing risk of both adenoma (ptrend= 0.04) and cancer (ptrend=0.08) with increasing calcium intake, with RRs for adenoma and cancer of 0.80 (IC 95%=0.62–1.03) and 0.72 (95% CI=0.47–1.10), respectively, in the fourth quartile compared to the first. A protective effect of dairy products on adenoma (RRQ4 vs. Q1= 0.80, 95% CI=0.62‐1.05, ptrend= 0.04) was observed and of milk consumption on colorectal cancer (RRQ4vs. Q1= 0.54, 95% CI=0.33–0.89, ptrend= 0.09), although the latter did not reach significance. Phosphorus intake also decreased the risk of adenoma (RRQ4 vs. Q1=0.70, 95% CI=0.54–0.90, ptrend= 0.005). No vitamin D effect was identified. Our data support the hypothesis that calcium, dairy products and phosphorus exert a protective effect at certain steps of the adenoma‐carcinoma sequence. © 2005 Wiley‐Liss, Inc.