Review Physical Activity and Risk of Lymphoma: A Meta-Analysis

Background: Physical activity has a protective effect on some types of cancer. The aim of the present meta-analysis was to explore the literature on the association between physical activity and risk of lymphoma. Methods: A meta-analysis was conducted for cohort and case–control studies examining the association between self-reportedphysical activity and riskof lymphoma.Dependingon statistical heterogeneity, a randomor fixed effects model was used to estimate the summary OR and corresponding 95 % confidence interval (CI). Results: Seven case–control studies and 5 cohort studieswere included.When data fromboth study designs were combined, no significant influence of physical activity on risk of lymphomawas found (pooledOR 0.90; 95 % CI: 0.79–1.02; P 0.10). Subgroup analysis revealed a significant protective influence of physical activity on risk of lymphoma in case–control studies (pooled OR 0.81; 95 % CI: 0.68–0.96; P 0.02). In contrast, cohort studies, which have a higher level of evidence than case–control studies, confirm the results of the primarymeta-analysis (pooled OR 1.02; 95%CI: 0.88–1.19; P 0.76). A subsequent subgroup analysis found no significant differences between results for Hodgkin lymphoma and non-Hodgkin lymphoma (c2 0.16; P 0.69), nor between results for recreational and occupational activities (c2 1.01; P 0.31). Conclusions: Epidemiologic research indicates no significant influence of physical activity on risk of lymphoma. Impact: Future research should examine the association between sedentary behavior and risk of lymphoma and investigate the dose–response and timing effect of physical activity on risk of lymphoma. Cancer Epidemiol Biomarkers Prev; 22(7); 1173–84. 2013 AACR