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(2) = 0.16; P = 0.69), nor between results for recreational and occupational activities (χ(2) = 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.