The relationship between physical activity, obesity, and lung cancer risk by smoking status in a large prospective cohort of US adults

AbstractPhysical activity has been associated with lower lung cancer risk in numerous studies with estimates ranging from 20 to 50% lower risk in the most versus the least active study participants. Underweight and obesity have also been associated with lower lung cancer risk, with a nonlinear, inverted U-shaped relationship. However, associations of physical activity and obesity with lung cancer are likely significantly confounded by smoking since individuals who smoke are generally less active and leaner than non-smokers, but few studies have examined these associations stratified by smoking status. Using data from 162,679 men and women who were cancer-free at enrollment (1992 –1993) in the American Cancer Society Cancer Prevention Study-II Nutrition Cohort, we examined associations of baseline recreational physical activity (MET-hours per week; none, 0.1 to<8.75 (reference), 8.75 –17.4, 17.5+ MET-hours/week), baseline body mass index (BMI, weight (kg)/height (m2);<18.5, 18.5 –22.0 (reference), 22.1–24.9, 25.0–29.9, 30.0+ kg/m2), and waist circumference (measured in 1997; sex-specific quartiles) in relation to lung cancer risk stratified by smoking status and years since quitting among former smokers (never, current, former  <10  years, former, 10–19 years, former 20+ years). Cox proportional hazards modeling computed hazard rate ratios (RR) and 95% confidence intervals (CI) while adjusting for potential confounders. During 2,384,546 person years ...
Source: Cancer Causes and Control - Category: Cancer & Oncology Source Type: research