Background: Conflicting evidence exists on the relationship between physical activity (PA) and incident hematologic malignancies. Herein, we used a large cohort study to examine this association.
Patients and methods: Sixty-five thousand three hundred twenty-two volunteers aged 50-76 years were recruited from 2000 to 2002. Incident hematologic malignancies (n = 666) were identified through 2009 by linkage to the Surveillance, Epidemiology, and End Results cancer registry. Hazard ratios (HRs) for hematologic malignancies associated with PA averaged over 10 years before baseline were estimated with Cox proportional hazards models, adjusting for factors associated with hematologic cancers or PA.
Results: There was a decreased risk of hematologic malignancies associated with PA (HR = 0.66 [95% confidence interval, 95% CI 0.51-0.86] for the highest tertile of all PA, P-trend = 0.005, and HR = 0.60 [95% CI 0.44-0.82] for the highest tertile of moderate/high-intensity PA, P-trend = 0.002). These associations were strongest for myeloid neoplasms (HR = 0.48 [95% CI 0.29-0.79] for the highest tertile of all PA, P-trend = 0.013, and HR = 0.40 [95% CI 0.21-0.77] for the highest tertile of moderate/high-intensity PA, P-trend = 0.016). There were also significant associations between PA and chronic lymphocytic leukemia/small lymphocytic lymphoma or other mature B-cell lymphomas except plasma cell disorders.
Conclusions: Our study offers the strongest epidemiological evidence, to date, to suggest an association between regular PA and dose-dependent risk reduction for most hematologic malignancies, particularly myeloid neoplasms.