Association of change in physical activity and body weight with quality of life and mortality in colorectal cancer: a systematic review and meta-analysis.

PURPOSE: A systematic review and a meta-analysis were performed to assess the associations between change over time in physical activity and weight and quality of life and mortality in colorectal cancer patients. METHODS: The PubMed, Embase, and Cochrane Central Register of Controlled Trials databases were searched for English language articles published between January 1, 1990 and October 7, 2013. These articles reported results for changes in physical activity and body weight, assessed at pre- to post-diagnosis or at post-diagnosis only. A random effects model was used to analyze pooled quality of life and mortality estimates. RESULTS: Seven eligible studies were identified and analyzed. Increased physical activity was associated with higher overall quality of life scores (N = 3 studies; standardized mean difference (SMD) = 0.74, 95 % confidence interval (CI) = 0.66-0.82), reduced disease-specific mortality risk (hazard ratio (HRpooled) = 0.70, 95 % CI = 0.55-0.85), and reduced overall mortality (HRpooled = 0.75, CI = 0.62-0.87) (N = 2 studies). Weight gain was not associated with disease-specific (HRpooled = 1.02, CI = 0.84-1.20) or overall (HRpooled = 1.03, CI = 0.86-1.19) mortality (N = 3 studies). CONCLUSIONS: Increased physical activity was associated with improved quality of life, a reduced risk of colorectal cancer, and overall mortality rate. Given the paucity of the literature published on this topic, this finding should be interpreted with caution.