Abstract B02: Recreational physical activity, sedentary time and the incidence of colorectal polyps in a screening population for colon cancer

Background: Despite the consistent association between regular recreational moderate to vigorous physical activity (rMVPA) and reduced risk of colorectal cancer (CRC), few studies have examined the effect of physical activity on carcinogenic development by examining colorectal adenomas (polyps). Furthermore, even fewer studies have examined the impact of sedentary behavior/time (ST) on the development of polyps. In this study we examined the associations between rMVPA and ST and the presence, number and type of colorectal polyps in a population undergoing screening for colorectal cancer in Calgary, Alberta, Canada. Methods: A cross-sectional study of 2,499 individuals undergoing colonoscopy at the Forzani & MacPhail Colon Cancer Screening Centre in Calgary, Canada was conducted. Physical activity levels and ST were characterized using hours of rMVPA, meeting cancer prevention recommendations (≥150 mins/wk of rMVPA) and hours of ST using self-reported data from the Long Form International Physical Activity Questionnaire. Unconditional logistic regression models were used to estimate the crude and adjusted odds ratios (OR) for presence of polyps associated with rMVP and ST. Results: Crude estimates for meeting cancer prevention guidelines (ORunadj=0.83, 95% CI: 0.70-0.98) and increasing rMVPA (ORunadj=0.75, 95% CI: 0.60-0.93 for 1-3 hrs/wk vs. 0) were associated with lower odds of having ≥1 polyp at screening. Effect estimates were attenuated in adjusted models. Threshold effects were observed for ST with significant associations observed for up to 20 hours/week of sitting time (ORadj per hour sitting=1.05, 95% CI: 1.01-1.09). Associations were strongest for rMVPA among females (ORadj=0.68, 95% CI: 0.48-0.97 for 1-3 hrs/wk vs. 0) and for ST among males (ORadj=1.74, 95% CI: 1.06-2.86 for 14-35hrs/wk of ST vs. 0-14 hrs/wk) Conclusions: In this large population undergoing colonoscopy screening for colorectal cancer, rMVPA was associated with reduced prevalence of polyps at screening, particularly among females. Even low amounts of regular ST (2-5hrs/day) were associated with the presence of polyps, particularly among males. Strategies aimed at reducing the amount of pre-carcinogenic colon lesions should combine increasing rMVPA and reducing ST. Citation Format: Darren R. Brenner, Demetra H. Yannitsos, Matthew Warkentin, Eileen Shaw, Nigel T. Brockton, S. Elizabeth McGregor, Susanna Town, Robert J. Hilsden. Recreational physical activity, sedentary time and the incidence of colorectal polyps in a screening population for colon cancer. [abstract]. In: Proceedings of the AACR Special Conference: Improving Cancer Risk Prediction for Prevention and Early Detection; Nov 16-19, 2016; Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(5 Suppl):Abstract nr B02.