Abstract
Several biological mechanisms linking physical activity with cancer have been proposed. However, the influence of specific components of physical activity (volume, type and intensity), and their interaction with adiposity and diet, on cancer-related biomarkers remain unclear. We used cross-sectional data on 7,219 men in the Health Professionals Follow-up Study (1992-1994) with C-reactive protein (CRP), interleukin-6 (IL6), tumor necrosis factor alpha receptor 2 (TNFαR2), adiponectin, C-peptide and triglycerides/high-density lipoprotein cholesterol ratio (TG/HDL). Details on physical activity, diet and adiposity were assessed by questionnaires. We used multivariable-adjusted linear regression analyses to estimate relative concentrations of biomarkers by physical activity. Total physical activity was favorably associated with all biomarkers in a fairly linear manner. Comparing the highest (63+ metabolic equivalent (MET)-hr/week) to the lowest (0-8.9 MET-hr/week) physical activity groups, the percent relative difference in concentration of biomarkers was -31% for CRP, -22% for IL6, -8% for TNFαR2, +9% for adiponectin, -22% for C-peptide, and -20% for TG/HDL. These differences were modestly attenuated after adjustment for adiposity. For the same total MET-hours of physical activity, the association was stronger for men engaging in both aerobic and resistance exercises compared to those engaging in aerobic only. However, no difference was found between those engaging in vigorous activities (≥20% of total MET-hours) compared to those who did smaller amount of vigorous activities. Physical activity showed similar associations for these biomarkers regardless of adiposity and dietary pattern. In conclusion, high physical activity, preferably aerobic plus resistance training, was associated with favorable cancer-related biomarkers.