Abstract
Background: Fish is the main dietary source of long-chain n-3 fatty acids, which have been suggested to play a protective role in colorectal cancer development in laboratory and animal studies. Human studies have not shown consistent results. We examined the association between intakes of fish and n-3 fatty acids from fish and colorectal cancer risk in men enrolled in the Physicians' Health Study.
Methods: The Physicians' Health Study began as a randomized trial to examine the effect of aspirin and β-carotene supplementation on cancer and cardiovascular disease. Fish intake was assessed at the 12-month follow-up with an abbreviated food-frequency questionnaire. Cox proportional hazards models were used to estimate multivariate relative risks for colorectal cancer for the categories of fish intake and quartiles of n-3 fatty acid intake.
Results: During 22 years of follow-up, 500 men had a confirmed diagnosis of colorectal cancer. Fish intake was inversely associated with colorectal cancer risk [multivariate relative risk (95% confidence interval) for highest versus lowest category, 0.60 (0.40-0.91); Ptrend = 0.01]. The inverse association was observed for both colon and rectal cancers. Our findings for n-3 fatty acids were similar to those for fish; the multivariate relative risk (95% confidence interval) of total colorectal cancer for the highest versus lowest quartile of n-3 fatty acids was 0.74 (0.57-0.95; Ptrend = 0.01).
Conclusions: Our results from this long-term prospective study suggest that intakes of fish and long-chain n-3 fatty acids from fish may decrease the risk for colorectal cancer. (Cancer Epidemiol Biomarkers Prev 2008;17(5):1136–43)
- fish
- n-3 fatty acids
- colorectal cancer
- prospective cohort
- risk
Footnotes
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Grant support: NIH R25 CA098566 and CA42182.
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Note: The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the NIH.
- Accepted February 20, 2008.
- Received November 15, 2007.
- Revision received January 23, 2008.