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The authors examined the association between circulating 25-hydroxyvitamin D(3) (25(OH)D(3)), the best indicator of total vitamin D exposure, and incident, sporadic colorectal adenoma risk in a pooled analysis of primary data from 3 colonoscopy-based case-control studies conducted in Minnesota, North Carolina, and South Carolina between 1991 and 2002.
The pooled study included 616 colorectal adenoma cases and 770 polyp-free controls. [Colorectal adenomas (polyps) are considered indicative of increased colon cancer risk.]
Multivariable logistic regression was used to estimate the association between circulating 25(OH)D(3) and colorectal adenoma risk. Stratified analyses and the likelihood ratio test were used to examine effect modification by various risk factors.
• In the pooled analysis, higher circulating 25(OH)D(3) concentrations were statistically significantly associated with decreased colorectal adenoma risk (highest vs. lowest quartile odds ratio = 0.59, 95% confidence interval: 0.41, 0.84).[Note: an odds ratio of 1.0 would indicate no difference. This ratio indicates the group with higher vitamin D levels were 41% less likely to have adenomas.]
• The observed inverse association was stronger among participants who used nonsteroidal antiinflammatory drugs regularly (highest vs. lowest quartile odds ratio = 0.33, 95% confidence interval: 0.19, 0.56). [Those in higher D group taking aspirin, NSAIDS, etc. were 67% less likely to have adenomas.]
Inverse associations between 25(OH)D(3) and colorectal adenoma did not differ substantially by other risk factors or by adenoma characteristics.
These findings support the hypothesis that greater vitamin D exposure may reduce the risk of colorectal adenoma and suggest that it may do so more strongly in combination with antiinflammatory agents.
Source: American Journal of Epidemiology, Sep 1, 2010.172(5):489-500. doi:10.1093/aje/kwq157, by Fedirko V, bostick RM, Goodman M, flanders Wd, Gross MD. Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA. [Email: email@example.com).