Objective

With combination-antiretroviral therapy, HIV-infected individuals live longer with an elevated burden of cancer. Given the high prevalence of smoking among HIV-infected populations, we examined the risk of incident cancers attributable to ever smoking cigarettes.

Design

Observational cohort of HIV-infected participants with 270 136 person-years of follow-up in the North American AIDS Cohort Collaboration on Research and Design consortium. Among 52 441 participants, 2306 were diagnosed with cancer during 2000-2015.

Main outcome measures

Estimated hazard ratios and population-attributable fractions (PAF) associated with ever cigarette smoking for all cancers combined, smoking-related cancers, and cancers that were not attributed to smoking.

Results

People with cancer were more frequently ever smokers (79%) compared with people without cancer (73%). Adjusting for demographic and clinical factors, cigarette smoking was associated with increased risk of cancer overall [hazard ratios = 1.33 (95% confidence interval: 1.18-1.49)]; smoking-related cancers [hazard ratios = 2.31 (1.80-2.98)]; lung cancer [hazard ratios = 17.80 (5.60-56.63)]; but not nonsmoking-related cancers [hazard ratios = 1.12 (0.98-1.28)]. Adjusted PAFs associated with ever cigarette smoking were as follows: all cancers combined, PAF = 19% (95% confidence interval: 13-25%); smoking-related cancers, PAF = 50% (39-59%); lung cancer, PAF = 94% (82-98%); and nonsmoking-related cancers, PAF = 9% (1-16%).

Conclusion

Among HIV-infected persons, approximately one-fifth of all incident cancer, including half of smoking-related cancer, and 94% of lung cancer diagnoses could potentially be prevented by eliminating cigarette smoking. Cigarette smoking could contribute to some cancers that were classified as nonsmoking-related cancers in this report. Enhanced smoking cessation efforts targeted to HIV-infected individuals are needed.