title: A 22-year prospective study of fish, n-3 fatty acid intake, and colorectal cancer risk in men.
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 beta-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, 0.63 (0.42-0.95); P trend = 0.02] [corrected] 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; P trend = 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.
authors.affiliation: Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032, USA. mh2825@columbia.edu
authors.forename: Megan N
authors.initials: MN
authors.lastname: Hall
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Chavarro
authors.forename: I-Min
authors.initials: IM
authors.lastname: Lee
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
mesh_terms: D000818:Animals; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D004032:Diet; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D005399:Fishes; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
chemical_list: D015525:Fatty Acids, Omega-3