Physical Activity Decreases Kidney Cancer Mortality.

ABSTRACT

BACKGROUND: To investigate associations of kidney cancer mortality with modifiable risk factors of obesity, physical activity, and smoking. METHODS: We evaluate baseline data from US National Health Information Survey from 1998 through 2004 linked to mortality data reporting deaths through 2006. The primary outcome variable was kidney cancer-specific mortality and primary exposure variables were self-reported physical activity and body mass index (BMI). We utilized multivariable adjusted Cox proportional hazards regression models, with delayed entry to account for age at survey interview. RESULTS: Among 222,163 individuals with complete follow-up data we identified 71 kidney cancer-specific deaths. In multivariate analyses, individuals who reported "any physical activity" were 50% less likely [adjusted hazard ratio (adjusted HR) 0.50, 95% CI 0.27-0.93, p = 0.028] to die of kidney cancer than non-exercisers, while obese individuals (BMI ≥ 30 kg/m2) were nearly 3 times more likely (adjusted HR 2.84, 95% CI 1.30-6.23, p = 0.009) compared to those of normal weight (BMI < 25 kg/m2). Compared to never smokers, former smokers were twice as likely to die of kidney cancer (adjusted HR 2.00, 95% CI 1.05-3.80, p = 0.034). CONCLUSION: Physical activity decreases and obesity increases the risk of kidney cancer mortality.