Long-term nitrite inhalant exposure and cancer risk in men who have sex with men: a prospective cohort study.

OBJECTIVES: Nitrite inhalants (poppers) are commonly used recreational drugs among men who have sex with men (MSM) and were previously associated with elevated rates of high-risk sexual behavior, HIV and HHV-8 seroconversion, and transient immunosuppressive effects in experimental models. Whether long-term popper use is associated with cancer risk among MSM in the HAART era is unclear.

DESIGN: Prospective cohort study of cancer risk in 3223 HIV-infected and -uninfected MSM in the Multicenter AIDS Cohort Study from 1996-2010.

METHODS: Poisson regression models were used to examine the association between heavy popper use (defined as daily or weekly use for at least one year) and risk of individual cancers or composite category of virus-associated cancers.

RESULTS: Among all participants, heavy popper use was not associated with increased risk of any individual cancers. Among HIV-uninfected men ages 50-70, heavy popper use was associated with increased risk of virus-associated cancer with etiologies linked to HPV, HHV-8, and EBV in models adjusted for demographics, number of sexual partners, immunological parameters (CD4 counts or CD4/CD8 ratios), and HBV/HCV (IRR, 3.24; 95% CI, 1.05-9.96) or sexually transmitted infections (IRR 3.03, 95% CI, 1.01-9.09), as was cumulative use over a 5-year period (IRR 1.012, 95% CI 1.003-1.021; p = 0.007). There was no significant association between heavy popper use and virus-associated cancer in HIV-infected men.

CONCLUSIONS: Long-term heavy popper use is associated with elevated risk of some virus-associated cancers with etiologies related to HPV, HHV-8, and EBV infections in older HIV-uninfected MSM independent of sexual behavior and immunological parameters.