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-reported physical activity and risk of lymphoma. Depending on statistical heterogeneity, a random or fixed effects model was used to estimate the summary OR and corresponding 95% confidence interval (CI). Results: Seven case-control studies and 5 cohort studies were included. When data from both study designs were combined, no significant influence of physical activity on risk of lymphoma was found (pooled OR = 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 primary meta-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 (χ