Risk factors of colorectal adenoma recurrence among individuals under 50 years of age compared to those 50 years of age or older.

1554 Background: Colorectal cancer incidence and mortality are increasing among individuals < 50 years of age. Data are limited regarding the epidemiology of colorectal adenomas in this younger age group. This study investigated and compared risk factors associated with recurrence of adenomas in individuals under and over 50 years of age. Methods: Pooled analyses from the Wheat Bran Fiber and Ursodeoxycholic Acid phase III, randomized, controlled clinical trials included 1,623 participants, aged 40-80 years. Each completed baseline questionnaires related to family history and lifestyle habits, had one or more colorectal adenomas removed at baseline, and had a follow-up colonoscopy during the trial (mean follow up 36 months). Univariate and multivariate logistic regression modeling estimated the association between age and colorectal adenoma recurrence, and evaluate multiple risk factors, while controlling for confounding factors. Results: A statistically significant increased trend was found for colorectal adenoma recurrence with increasing age ( Ptrend= < 0.001). Multivariate logistic regression revealed that risk factors significantly associated with adenoma recurrence in the ≥50 age group (n = 1,523) included history of previous polyps, characteristics of adenomas removed at baseline (multiple adenomas and villous feature), current smoking, and an increased waist circumference. Although risk profile in the < 50 age group (n = 95) shared similarities with that in the ≥50 age group (e.g., current smoking), there were a few notable differences: history of previous polyps was a more prominent predictor for recurrence for the < 50 (OR< 50 = 4.76 and OR≥50 = 1.33, Pinteraction = 0.042), whereas baseline characteristics of adenomas were more important for the ≥50 (multiple adenomas: OR< 50 = 0.40 and OR≥50 = 2.28, Pinteraction = 0.043). Conclusions: Predisposition to colorectal adenoma is a more important risk factor for recurrence in the < 50 as compared to the ≥50. Future studies need to identify susceptibility factors contributing to the increasing incidence of colorectal cancer in this younger age group.