Pre- and post-diagnosis physical activity is associated with survival benefits of colorectal cancer patients: a systematic review and meta-analysis.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational cohort studies
PubMed 27437765 · doi:10.18632/oncotarget.10603
What was done
A systematic review and meta-analysis of studies in PubMed, Cochrane Library, and Web of Science published through January 2016. Authors identified 11 studies covering 17,295 colorectal cancer patients followed for 3.8 to 11.9 years. Using random-effects models, they pooled adjusted relative risks (RRs) and 95% confidence intervals (CIs) for total and colorectal cancer-specific mortality in relation to physical activity performed before or after cancer diagnosis. Publication bias was evaluated using Begg's test.
What was found
Pre-diagnosis physical activity was associated with reduced overall mortality (RR = 0.81, 95% CI 0.72-0.91) and reduced colorectal cancer-specific mortality (RR = 0.79, 95% CI 0.71-0.89). Post-diagnosis physical activity was likewise associated with reduced overall mortality (RR = 0.71, 95% CI 0.63-0.81) and reduced cancer-specific mortality (RR = 0.77, 95% CI 0.63-0.94). Similar inverse associations were observed when comparing high-level exercise to low-level activity or inactivity. Begg's test showed no obvious evidence of publication bias.
Why it matters
This review aggregates observational data demonstrating that pre- and post-diagnosis physical activity is associated with a 19% to 29% lower risk of mortality in colorectal cancer patients. It supports incorporating physical activity recommendations into cancer survivorship care plans.
Limits
The included evidence is entirely observational, making findings vulnerable to reverse causation (healthier patients with lower disease burden being more physically active) and unmeasured confounding. The abstract does not detail specific activity types, durations, or disease stages, and physical activity was likely self-reported across studies.
Cited by
- supports Studies demonstrate that pre-diagnosis exercise is associated with improved post-diagnosis cancer survival outcomes, independent of post-diagnosis exercise.