Relationship explored between physical activity and lymphoma

(HealthDay)—High levels of physical activity may lower the risk for developing lymphoma, according to a review/meta-analysis published online Oct. 6 in BMC Cancer.

Gwynivere A. Davies, M.D., M.P.H., from the Juravinski Cancer Centre-Hamilton Health Sciences in Canada, and colleagues conducted a systematic literature review/meta-analysis to examine the association between physical activity and incident lymphoma. Eighteen studies (nine cohort, nine case-control) were included in the final analysis.

The researchers found that for all lymphoma, comparing the highest with the lowest activity categories showed physical activity was protective (relative risk, 0.89; 95 percent confidence interval, 0.81 to 0.98). In a sensitivity analysis, the effect persisted in case-control studies (relative risk, 0.82; 95 percent confidence interval, 0.71 to 0.96) but not in cohort studies (relative risk, 0.95; 95 percent confidence interval, 0.84 to 1.07). A subgroup analysis showed some protective effect of physical activity for non-Hodgkin lymphoma (relative risk, 0.92; 95 percent confidence interval, 0.84 to 1.00) but not for Hodgkin lymphoma (relative risk, 0.72; 95 percent confidence interval, 0.50 to 1.04). A protective effect was demonstrated in a dose-response analysis, with a 1 percent reduction in risk per three metabolic equivalent of task (MET) hours/week (relative risk, 0.99; 95 percent confidence interval, 0.98 to 1.00; P = 0.034).

"Dose response analysis supports these conclusions, with a linear decrease in incidence seen with increasing recreational physical activity," the authors write.