Selenium and colorectal adenoma: results of a pooled analysis.

Journal of the National Cancer Institute
Q1
Nov 2004
Citations:167
Influential Citations:7
Observational Studies (Human)
83
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Methods
Participants: adults who recently had a colorectal adenoma removed during colonoscopy. Study design: three multicenter randomized trials (Wheat Bran Fiber Trial; Polyp Prevention Trial; Polyp Prevention Study). Selenium measured in blood at baseline; Data pooled; Analysis used unconditional logistic regression and random-effects model; Two-sided tests; Combined dataset included 1,763 participants with selenium data across trials.
Intervention
Wheat Bran Fiber Trial: high-fiber cereal supplement vs low-fiber supplement for 3 years; Polyp Prevention Trial: vitamin C, vitamin E, and beta-carotene supplementation for 4 years; Polyp Prevention Study: low-fat, high-fiber diet containing fruits and vegetables vs normal diet for 4 years
Results
Higher baseline blood selenium was associated with lower odds of adenoma recurrence in the pooled analyses. Highest versus lowest quartile OR = 0.66 (95% CI 0.50–0.87); P-trend = 0.006. For large adenomas, OR = 0.57 (95% CI 0.34–0.95). Linear decrease in odds with increasing selenium beyond ~100 ng/mL. The inverse association supports prior findings that higher selenium status may reduce colorectal neoplasia risk; more research is needed to determine optimal selenium dose and chemical form for cancer prevention.
Limitations
Differences in trial designs and sampling across the three trials; selenium was measured with different assays across laboratories; potential misclassification of recurrences due to year-1 colonoscopy as a 'clean-out'; participants were volunteers with prior adenomas, limiting generalizability; inability to determine the optimal selenium dose or chemical form; post-hoc pooling may be affected by heterogeneity.

Abstract

BACKGROUND Secondary analyses of data from a large randomized clinical trial have suggested that intake of the trace element selenium reduces risk of colorectal neoplasia, but epidemiologic studies have not shown a consistent protective association. ...