Sedentary Behavior and Colorectal Adenoma – Is it a Risk Factor Independent of Physical Activity?

Abstract

Colorectal cancer is associated with a sedentary lifestyle. Emerging evidence indicate that sedentary behavior is distinct from physical inactivity (ie. too much sitting vs too little exercise) and may have physiologically distinct effects. Prolonged sedentary time is associated with increased all-cause mortality and colorectal carcinoma independent of physical activity levels. The relationship with colorectal adenoma, however, is less well defined. The objective is to determine whether colorectal adenoma are associated with sedentary behavior (defined by sitting hours) independent of physical activity levels. A cross-sectional study was performed as per STROBE guidelines. Eligible subjects (Table 1, Eligibility criteria), aged 45-70 years, scheduled for ambulatory colonoscopy, were prospectively recruited from December 2013 to January 2015. Interviews and anthropometric assessment was conducted by research coordinators. Physical activity data was collected using the validated IPAQ Long questionnaire. Physical activity was characterized both as continuous and categorical variables. Sedentary time was separately measured using the total time reported sitting per week. Baseline assessment was performed prior to colonoscopy to avoid bias. All colonoscopies were performed by gastroenterologists from a tertiary hospital. All polyps were removed or biopsied if removal was not feasible. Histology was reported by a pathologist blinded to the anthropometric and physical activity data. Continuous and categorical data were summarized by median (interquartile range) and frequency (proportion) respectively. Logistic regression was used to identify risk factors of adenoma. 124 patients undergoing colonoscopies were analyzed. 26 patients (21%; 95% CI: 14.7% to 29.0%) had adenoma. Baseline characteristics are reported in Table 2. There was no difference in sitting hours between patients with and without adenoma (2520 vs 2250 minutes, P = .711) after correction for potential confounders (ie, age, gender, obesity, physical activity, smoking).