Body mass index as a predictor of colorectal neoplasia in ethnically diverse screening population.

Background: Recent guidelines from the American College of Gastroenterology for screening for colorectal cancer have included obesity as an important risk factor. The recommendation for screening obese people at earlier age was tempered by the need for more data regarding obesity and colorectal neoplasia.
Aims: We designed a cross-sectional study to further examine the predictive value of obesity for colorectal adenomas in asymptomatic patients.
Methods: We prospectively collected demographic, medical, lifestyle, and dietary history from asymptomatic patients presenting for screening colonoscopy. Patients underwent complete colonoscopy using high-definition colonoscope to detect colorectal adenomas. We defined advanced neoplasia as large (≥ 1 cm) adenoma, villous adenoma, high-grade dysplasia or cancer.
Results: Six hundred patients with median age of 56 years completed the study. Over 40% of these patients did not consider themselves Caucasian, and less than 5% had a first-degree relative with colorectal cancer. Overall, 40 patients (6.7%) had advanced neoplasia and 216 (36.3%) had any adenoma. There were 185 obese patients (30.8%), who had a prevalence of 44.3% for any adenoma and 13.0% for advanced neoplasia. After multivariate analysis, obesity [body mass index (BMI) ≥ 30 kg/m(2)] was significantly associated with increased risk of advanced neoplasia [odds ratio (OR) = 3.83; 95% confidence interval (CI): 1.94-7.55].
Conclusions: Obesity was associated with advanced neoplasia in this screening population. Our data regarding the association of colorectal neoplasia with this modifiable risk factor has implications for screening and prevention of colorectal cancer.