Experimental data support multiple roles for fatty acids in colorectal carcinogenesis. We examined dietary fatty acids and incidence of colorectal cancer, and evaluated effect modification by sex and stage of disease among a population-based cohort of 61,321 Singapore Chinese that was established between 1993 and 1998. As of December 31, 2005, 961 incident colorectal cancers were diagnosed. Presented hazard ratios (HRs) are for highest versus lowest quartiles with adjustment for potential confounders.

Among women, we observed a dose-dependent, positive association between saturated fat and localized colorectal cancer (Dukes A or B) [(HR=1.69, 95% confidence interval (CI)=1.08-2.63, p for trend=0.01)]. No such associations were noted in men (p for interaction by sex=0.04). Marine n-3 polyunsaturated fatty acid (PUFA) intake was positively associated with advanced disease (Dukes C or D) (HR=1.33, 95% CI=1.05-1.70, p for trend=0.01), regardless of sex.

The association with marine n-3 PUFAs was strongest among those with the shortest (<pr=5years) duration of follow-up (HR=1.49, 95% CI=1.00-2.21, p for trend=0.04).

In contrast, we observed a small, albeit imprecise, inverse association with marine n-3 PUFAs for localized colorectal cancer among those with the longest duration of follow-up (>10 years) (HR=0.62, 95% CI=0.29-1.34, p for trend=0.55). Our findings suggest that subtypes of fatty acids may differentially influence risk of colorectal cancer of a specified stage. Copyright (c) 2008 Wiley-Liss, Inc.