Physical Activity and Mortality in Cancer Survivors: A Systematic Review and Meta-Analysis

Background: Recommendations for improved survival after cancer through physical activity (PA) exist, although the evidence is still emerging. Our primary objective was to conduct a systematic review and meta-analysis of the association between prediagnosis and postdiagnosis PA and survival (cancer-specific, all-cause, and cardiovascular disease mortality) for all cancers and by tumor site. Secondary objectives were to examine the associations within population subgroups, by PA domain, and to determine the optimal dose of PA related to survival. Methods: PubMed, EMBASE, and SportsDiscus databases were searched from inception to November 1, 2018. DerSimonian-Laird random-effects models were used to estimate the summary hazard ratios (HRs) and 95% confidence intervals (CI) for primary and secondary analyses and to conduct dose-response analyses. Results: Evidence from 136 studies showed improved survival outcomes with highest vs lowest levels of prediagnosis or postdiagnosis total or recreational PA for all-cancers combined (cancer specific mortality: HR = 0.82, 95% CI = 0.79 to 0.86, and HR = 0.63, 95% CI = 0.53 to 0.75, respectively) as well as for 11 specific cancer sites. For breast and colorectal cancers, greater reductions were observed for postdiagnosis PA (HR = 0.58-0.63) compared with prediagnosis PA (HR = 0.80-0.86) for cancer-specific and all-cause mortality. Survival benefits through PA were observed in most subgroups (within sex, body mass index, menopausal status, colorectal subtypes, and PA domain) examined. Inverse dose-response relationships between PA and breast cancer-specific and all-cause mortality were observed, with steep reductions in hazards to 10-15 metabolic equivalent hours per week. Conclusion: Higher prediagnosis and postdiagnosis levels of PA were associated with improved survival outcomes for at least 11 cancer types, providing support for global promotion of PA guidelines following cancer.