Abstract
The changing profile of lifestyles and their intricate relationships with smoking indicate the importance of accounting for smoking status when assessing cancer preventability. We assessed the association of body mass index, weight change, alcohol intake and physical activity with risk of total carcinoma among 53,195 smokers and 62,842 nonsmokers in two prospective cohorts. Then, leveraging the national prevalence estimates, we calculated the population attributable risk (PAR) for healthy lifestyle defined as body mass index ≥18.5 and <27.5 kg/m(2) , mid-life weight change of ≤20 pounds, no or moderate alcohol drinking (≤1 and 2 drinks/day for women and men, respectively) and weekly moderate or vigorous physical activity of at least 150 min. The PAR (95% CI) for healthy lifestyle was 18% (14-22%) in nonsmokers and 14% (10-19%) in smokers among women, and 20% (12-27%) in nonsmokers and 11% (5-17%) in smokers among men. While adiposity accounted for a substantially higher proportion of carcinoma cases in nonsmokers than smokers (16% vs. 2% in women, 15% vs. 2% in men), alcohol contributed more in smokers than nonsmokers (7% vs. 3% in women, 8% vs. 1% in men). When more strict criteria were used to define healthy lifestyle, the PAR estimates further increased (for women: 37% in smokers and 32% in nonsmokers; for men: 15% and 24%, respectively). In conclusion, lifestyle modification has great potential to reduce cancer risk in both smokers and nonsmokers. Weight control and reducing alcohol consumption should be prioritized for cancer prevention in nonsmokers and smokers, respectively.