Recreational drug use and risk of Kaposi's sarcoma in HIV- and HHV-8-coinfected homosexual men.

Experimental data suggested that exposure to recreational drugs might adversely affect antitumor immunity, which led us to examine the hypothesis that use of marijuana, cocaine, poppers, and amphetamines might increase the risk of Kaposi's sarcoma (KS) in HIV- and HHV-8-coinfected homosexual men. We analyzed data prospectively collected from the Multicenter AIDS Cohort Study (MACS) between 1984 and 2002. Among the 1335 HIV- and HHV-8-coinfected white men, 401 KS cases were identified. Multivariable Cox regression models were used to estimate the effects of time-varying recreational drug use on KS risk adjusting for potential confounders. The effects of both recent use (6 months prior) of recreational drugs and lagged exposure (i.e., use from 3 and 5 years prior) were examined. We did not observe any clear association with KS for recent use of any of the four drugs. In the analyses using lagged exposures, KS risk was associated with use of poppers 3-5 years prior [hazard ratio (HR)(3 years prior) = 1.27, 95% CI (0.97-1.67), HR(5 years prior) = 1.46 (1.01-2.13)]. However, no clear dose-response relationship was observed. These findings do not support a biological association between use of these substances and KS development in HIV- and HHV-8-coinfected homosexual men.