Body mass index increases risk of colorectal adenomas in men with Lynch syndrome: the GEOLynch cohort study.

ABSTRACT

PURPOSE: High body mass index (BMI) is an established risk factor for sporadic colorectal cancer. Still, the influence of BMI on hereditary colorectal cancer (eg, Lynch syndrome [LS]), is unknown. The objective of this study was to assess whether BMI is associated with colorectal adenoma occurrence in persons with LS. PATIENTS AND METHODS: A prospective cohort study of 486 patients with LS was conducted. Cox regression models with robust sandwich estimates controlling for age, sex, extent of colon surgery, smoking, and alcohol intake were used to evaluate associations between BMI, height, weight, weight change, and risk of colorectal adenomas. Analyses were performed separately for those without (incident cohort; n = 243) and those with (prevalent cohort; n = 243) a history of colorectal cancer neoplasms at baseline. RESULTS: A statistically significant association between current overweight (≥ 25 kg/m(2)) and developing colorectal adenomas was seen among men in the incident cohort (overweight v normal weight hazard ratio [HR], 8.72; 95% CI, 2.06 to 36.96). This association was not observed among women (overweight v normal weight HR, 0.75; 95% CI, 0.19 to 3.07), nor was it observed in the prevalent cohort. In the incident cohort, height was statistically significantly associated with a decreased risk of adenomatous polyps among men (per 5 cm HR, 0.43; 95% CI, 0.23 to 0.83), but the association between weight and adenomatous polyps among men was of marginal significance (per 5 kg HR, 1.17; 95% CI, 1.00 to 1.37). No statistically significant associations were observed among women in either the incident cohort or the prevalent cohort. CONCLUSION: Excess body weight increased the risk of incident colorectal adenomas in people with LS. This increased risk was seen only in men.