We investigated whether the effect of smoking on the incidence of smoking-related cancers differs by HIV-infection status, if sex modifies the impact of risk factors for smoking-related cancers, and the sex-specific attributable risk of smoking on cancer incidence.
Data from two large prospective studies in the United States were analyzed: 6789 men in the Multicenter AIDS Cohort Study from 1984 through 2018 and 4423 women in the Women's Interagency HIV Study from 1994 through 2018.
Incidence rates, relative risks, and adjusted population attributable fractions (PAFs) were calculated for smoking-related cancers.
During study follow-up, there were 214 incident smoking-related cancers in the men and 192 in the women. The age-adjusted incidence ratess for smoking-related cancers were higher in the women (392/100 000) than for the men (198/100 000; P < 0.01) and higher for people living with HIV (PLWH, 348/100 000) than for those without HIV (162/100 000; P < 0.01). Unadjusted incidence rates in PLWH were higher than in those without HIV when stratifying by cumulative pack-years of smoking (all P values <0.01). In adjusted interaction models, the effects of cumulative pack-years of smoking were significantly stronger in women. The adjusted PAFs for smoking-related cancers were nonsignificantly higher in the women than in the men (39 vs. 28%; P = 0.35).
HIV looks to be an independent risk factor for smoking-related cancers and women appear to have a greater risk than men. These results highlight the need for interventions to help PLWH, especially women, quit smoking and sustain cessation to reduce their risk of smoking-related cancers.