Re: Asthma and the risk of lung cancer. Findings from the adverse childhood experiences (ACE)

Using data from 8,896 men and women aged 50-89 years from the Adverse Childhood Experiences Study who were free of a self-reported history of lung cancer or any cancer at baseline, we examined the association between self-reported asthma and incident lung cancer. The prevalence of smoking was 33% among those who developed lung cancer (n = 52) and 7% among those who did not. Asthma was reported by 17% of adults who developed lung cancer and by 9% of those who did not. After adjustment for age, gender, race/ethnicity, educational attainment, smoking status, number of cigarettes smoked per day, and growing up with a parent who smoked the risk of lung cancer was 2.1 (95% CI: 1.0, 4.4) times greater among adults with a history of asthma compared to those without. Among nonsmokers, a similar result was observed, although it did not attain statistical significance (RR: 2.1; 95% CI: 0.9, 5.1). Smoking-attributable lung cancer incidence and mortality are in part a function of the prevalence of smoking in the population. Thus, decreases in the prevalence of smoking in the United States that have occurred since its peak in the 1960s will inevitably result in a decline in the proportion of lung cancer in the population caused by smoking. We hope that our findings and those of others will stimulate research of the biologic mechanism(s) underlying the occurrence of lung cancer among nonsmokers so that possible treatments and prevention strategies may be developed.