UC San Diego

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.