Fish consumption and the risk of colorectal cancer: the Ohsaki Cohort Study.

BACKGROUND: Evidence from laboratory and animal studies suggests that high fish consumption may reduce the risk of colorectal cancer, but the results of studies in humans have been inconsistent. The objective of this study was to prospectively examine the association between fish consumption and the risk of colorectal cancer incidence in Japan, where fish is widely consumed. METHODS: We analysed data from 39 498 men and women registered in the Ohsaki National Health Insurance Cohort Study who were 40-79 years old and free of cancer at the baseline. Fish consumption was assessed at the baseline using a self-administered food frequency questionnaire. RESULTS: During 9 years of follow-up, we identified 566 incident cases of colorectal cancer (379 men and 187 women). The hazard ratios and 95% confidence intervals (CIs) for colorectal cancer incidence in the highest quartile of fish consumption compared with the lowest quartile were 1.07 (95% CIs; 0.78-1.46, P-trend=0.43) for men, and 0.96 (95% CIs; 0.61-1.53, P-trend=0.69) for women. CONCLUSION: The results of this prospective cohort study revealed no association between fish consumption and the risk of colorectal cancer.