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 (P-trend= 0.04) and cancer (P-trend=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. Q(I) = 0.80, 95 % CI = 0.62-1.05, P-trend = 0.04) was observed and of milk consumption on colorectal cancer (RRQ4 (vs.) (Q1) = 0.54, 95 % CI = 0.33-0.89, P-trend = 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, P-trend= 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. (c) 2005 Wiley-Liss, Inc.