Overall, selenium did not prevent colorectal adenomas and showed only modest benefit in patients with baseline advanced adenomas. With limited benefit and similar increases in T2D to other trials, selenium is not recommended for preventing colorectal adenomas in selenium-replete individuals.

A direct relation between body mass index (BMI) and risk of colorectal adenomas and cancer has been reported, but few studies have had adequate sample size for conducting stratified analyses by sex, family history, colorectal subsite, or features of metachronous lesions. Data from 8,213 participants in 7 prospective studies of metachronous colorectal adenomas were pooled to assess whether the association between BMI and metachronous neoplasia varied by these factors. A statistically significant direct association between BMI and the odds of nonadvanced adenomas (P(trend) < 0.001) was observed, while the relation for advanced adenomas was of marginal significance (P(trend) < 0.07). In sex-stratified analyses, obesity was statistically significantly associated with the odds of any metachronous lesion among men (odds ratio = 1.36, 95% confidence interval: 1.17, 1.58) but not among women (odds ratio = 1.10, 95% confidence interval: 0.89, 1.37). The associations with BMI appeared to be limited to proximal neoplasia, with statistically significant results for BMI and proximal (P(trend) < 0.001), but not distal (P(trend) < 0.85), neoplasia. Exploratory analyses indicated that BMI was significantly related to most histologic characteristics of metachronous adenomas among men but not among women. Our results provide further support for the association between BMI and metachronous colorectal adenomas, particularly among men, thereby indicating that body size may affect colorectal carcinogenesis at comparatively early stages.

Red meat intake has been shown to be associated with higher risk of colorectal cancer. Though the exact mechanisms responsible for this association remain unknown, several tumorigenic properties of meat have been proposed. One well-supported biologic mechanism is elevated exposure to the genotoxic formation of heterocyclic amines (HCAs), which occur when meat is cooked at high temperatures for a long period of time. We prospectively assessed the relation between type of meat, meat preparation method, doneness, a metric of HCAs and other mutagens and colorectal adenoma recurrence among 869 participants in a chemoprevention trial of ursodeoxycholic acid. Unconditional logistic regression analyses were used to estimate odds ratios (ORs) and associated 95% confidence intervals (CIs). Most meat variables assessed were positively but weakly associated with recurrence of any adenoma. In contrast, recurrence of advanced or multiple adenomas was more strongly associated with a number of the meat exposure variables evaluated. For recurrence of advanced lesions, significant associations were detected among individuals in the highest when compared with the lowest tertile of intake for pan-fried red meat (OR = 1.85; 95% CI = 1.10-3.13) and well/very well done red meat (OR = 1.71; 95% CI = 1.02-2.86). Significant positive associations were shown for recurrence of multiple adenomas and the following variables: processed meat (OR = 1.83; 95% CI = 1.10-3.04), pan-fried red meat (OR = 1.63; 95% CI = 1.01-2.61), well/very well done red meat (OR = 1.68; 95% CI = 1.03-2.74), 2-amino-3,4,8-trimethylimidazo[4,5,-f]quinoxaline (OR = 1.74; 95% CI = 1.07-2.82) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (OR = 1.68; 95% CI = 1.03-2.75). Our results support a meat mutagen exposure hypothesis as a potential mechanism for recurrence of clinically significant adenomatous polyps.

Limited-duration celecoxib prevents adenoma recurrence in patients with prior high-risk adenomas, in whom strategies to minimize cardiovascular toxicity might be feasible.

Background: The consistent association between obesity and colorectal cancer is thought to be explained by metabolic disturbances common, but not exclusive, to the obese. Methods: We assessed the relation between metachronous neoplasia and the components of metabolic syndrome (MetS) as defined by the National Cholesterol Education Program's Adult Treatment Panel III in 2,392 participants of two previously conducted chemoprevention trials. Waist circumference, fasting plasma glucose, trigylcerides, high-density lipoprotein, and systolic and diastolic blood pressure were measured at baseline. Results: MetS classification was associated with increased odds of metachronous neoplasia among women [odds ratio (OR), 1.37; 95% confidence interval (95% CI), 1.01-1.85] but not among men (OR, 0.99; 95% CI, 0.81-1.21). High waist circumference in men (OR, 1.41; 95% CI, 1.15-1.72) and women (OR, 1.41; 95% CI, 1.05-1.90) and elevated fasting glucose in women (OR, 1.46;