Fish consumption and risk of colorectal cancer

The association between fish consumption and risk of colorectal cancer was investigated in a population-based, incidence density case control study from northern Israel, the Molecular Epidemiology of Colorectal Cancer study. Food frequency questionnaire data were used from 1,869 cases and 1,777 controls ascertained and recruited between March 31, 1998 and February 14, 2005. Questionnaire data included three specific fish categories: canned tuna, mackerel/salmon/sardines, and cooked/fried fish. Multivariate unconditional logistic regression was used to assess the association between each fish consumption variable and risk of colorectal cancer. After adjusting for age, sex, and ethnicity consumption of canned tuna was associated with reduced risk of colorectal cancer. Participants who consumed canned tuna had an 18% reduced risk of colorectal cancer compared to those who never consumed canned tuna (odds ratio, 0.82; 95% confidence interval, [0.71, 0.94]). Comparing the highest tertile of fish consumption (1+ serving/week) to the lowest tertile of fish consumption (0 servings/month), canned tuna was associated with a 24% reduction of colorectal cancer risk. Adjusting known risk factors and potential confounders, consumption of mackerel/salmon/sardines was associated with a 27% reduced risk of colorectal cancer when comparing the highest and lowest tertiles of consumption (1+ serving/week vs. 0 servings/month). Consumption of cooked/fried fish was not associated with risk of colorectal cancer at any level of consumption. Data from this planned interim analysis suggest that diets characterized by the consumption of canned tuna as well as mackerel, salmon, and sardines are associated with reduced risk of colorectal cancer. Cooked and fried fish consumption was not associated with risk of colorectal cancer. This finding is consistent with animal studies that have examined the association between omega-3 fatty acids and colon tumor growth, indicating that omega-3 fatty acids inhibit colon carcinogenesis.