Modeling how substitution of sedentary behavior with standing or physical activity is associated with health-related quality of life in colorectal cancer survivors

PURPOSE: Previous research indicates that sedentary behavior is unfavorably associated with health-related quality of life (HRQoL) of colorectal cancer (CRC) survivors. Using isotemporal substitution modeling, we studied how substituting sedentary behavior with standing or physical activity was associated with HRQoL in CRC survivors, 2-10 years post-diagnosis. METHODS: A cross-sectional study was conducted in stage I-III CRC survivors (n = 145) diagnosed at Maastricht University Medical Center+, the Netherlands (2002-2010). Sedentary, standing, and physical activity time were measured by the thigh-mounted MOX activity monitor. HRQoL outcomes comprised global quality of life, physical, role, and social functioning, and disability (scales: 0-100), fatigue (20-140), and depression and anxiety (0-21). Isotemporal substitution modeling was applied to analyze associations with HRQoL of substituting sedentary time with equal time in standing or physical activity. RESULTS: On average, participants spent 10.2 h/day sedentary (SD, 1.7), 3.4 h/day standing (1.3), and 1.7 h/day in physical activity (0.8). In confounder-adjusted isotemporal models, substituting sedentary time with standing or with physical activity was associated with significantly better physical functioning (regression coefficient [beta], i.e., difference in outcome score per 1 h/day of sedentary time substituted with standing or physical activity, 3.1; 95 % confidence interval [CI] 0.5, 5.7; and 5.6; 0.7, 10.6, respectively). Substituting sedentary time with standing was also associated with significantly lower disability (beta, -3.0; 95 % CI -4.9, -1.1) and fatigue (-4.0; -7.6, -0.3). CONCLUSIONS: Our results suggest that substituting sedentary behavior with standing or physical activity may be beneficially associated with certain HRQoL outcomes in CRC survivors. Prospective studies are warranted to confirm whether actual substitution of sedentary behavior with these activities may improve HRQoL in CRC survivors.