Cessation of cigarette smoking and the impact on cancer incidence in human immunodeficiency virus-infected persons: The data collection on adverse events of anti-HIV drugs study

Background Cancers are a major source of morbidity and mortality for HIV-positive persons on combination antiretroviral therapy, while the clinical benefits of smoking cessation are not well established. Methods Participants were followed from 1 January 2004 until first cancer diagnosis, death, or 1 February 2016. Smoking status was defined as ex ( 5 years since stopping), current, and never smokers. Outcomes considered were any cancer, lung cancer, other smoking-related excluding lung and smoking-unrelated cancers. Adjusted incidence rate ratios (aIRR) were calculated using Poisson regression, adjusting for demographic and clinical factors. Results 35442 persons from the D:A:D study contributed 309803 person years of follow-up. At baseline, 49% of people were current smokers, 21% were ex-smokers, 30% had never smoked. Incidence of all cancers combined (N=2183) was highest <1 year after smoking cessation compared to never smokers (aIRR: 1.66 95%CI: 1.37, 2.02) and not significantly different from never smokers 1-2 years after cessation. Lung cancer incidence (N=271) was elevated <1 year after cessation (aIRR: 19.08 95%CI: 8.10, 44.95) and remained 8-fold higher 5 years after smoking cessation (aIRR: 8.69 95%CI: 3.40, 22.18). Incidence of other smoking-related cancers (N=622) excluding lung was elevated in the first year after cessation (aIRR: 2.06 95%CI: 1.42, 2.99) and declined to a level similar to non-smokers thereafter. Incidence of smoking-unrelated cancers (N=1290) was unrelated to smoking status. Conclusion Lung cancer incidence remained elevated for more than 5 years after smoking cessation. Deterring uptake of smoking and smoking cessation efforts should be a priority to reduce the future risk of cancer.