Men who spend the most time engaged in sedentary behaviours are at greatest risk for recurrence of colorectal adenomas, benign tumours that are known precursors of colorectal cancers, according to results presented at the 12th Annual AACR International Conference on Frontiers in Cancer Prevention Research, held Oct. 27–30.
The majority of colorectal cancers arise from precursors called colorectal adenomatous polyps, or colorectal adenomas, which can be removed during a colonoscopy. Although there is extensive evidence supporting an association between higher overall levels of physical activity and reduced risk of colorectal cancer, few studies have focused on the impact of sedentary behaviour on colorectal cancer risk.
“Sedentary behaviour is emerging as a risk factor for poor health,” said Christine L. Sardo Molmenti, Ph.D., M.P.H., postdoctoral research fellow in the Department of Epidemiology at Columbia University Mailman School of Public Health in New York. “Even among those who fulfil daily recommendations for physical activity, lengthy periods of sedentary behaviour have been associated with early morbidity and mortality, leading to the ‘active couch potato’ paradigm.
“To our knowledge, this study is the first to specifically investigate the association between sedentary behaviour and recurrence of colorectal adenomas. Given the substantial increase in risk of colorectal adenoma recurrence (45 percent) we observed for men with the highest sedentary time, we believe it would be beneficial to see ‘reduce prolonged sitting time’ added to the list of public health recommendations currently in place for health promotion and disease prevention.”
Sardo Molmenti and colleagues performed a pooled analysis of participants of two randomized, double-blind, placebo-controlled phase III clinical trials conducted at the University of Arizona Cancer Centre in Tucson and the Mel and Enid Zuckerman College of Public Health: The Wheat Bran Fibre Study and the Ursodeoxycholic Acid Trial.
All participants in the trials had one or more colorectal adenomas removed during a colonoscopy conducted in the six months prior to their trial enrolment. Among the participants were 1,730 who had completed a self-administered questionnaire that included questions about leisure, recreational, household, and other categories of activity at enrolment, and had undergone a follow-up colonoscopy.
When the researchers analysed all the data together, they found no association between activity type and colorectal adenoma recurrence. However, when they examined the data for men and women separately, they found that men who reported spending more than 11.38 hours a day engaged in sedentary behaviours, such as writing, typing or working on a computer, and reading, were 45 percent more likely to experience colorectal adenoma recurrence compared with men who spent fewer than 6.90 sedentary hours a day. No association between sedentary time and colorectal adenoma recurrence was observed for women…READ MORE