HIV-1 Viremia and Cancer Risk in 2.8 Million People: the South African HIV Cancer Match Study.

Background: Most research on HIV-1 viremia and cancer risk is from high-income countries. We evaluated the association between HIV-1 viremia and the risk of various cancer types among people with HIV (PWH) in South Africa.

Methods: We analysed data from the South African HIV Cancer Match study, based on laboratory measurements from the National Health Laboratory Services and cancer records from the National Cancer Registry from 2004-2014. Using Cox proportional hazards models, we estimated hazard ratios (HR) for cancer incidence per unit increase in time-updated Log10 HIV-1 RNA viral load copies/mL. We created partially adjusted (sex, age, calendar year) and fully adjusted models (additionally including time-updated CD4 count).

Results: We included 2,770,200 PWH with 10,175 incident cancers; most common were cervical cancer (N=2,481), Kaposi sarcoma (N=1,902), breast cancer (N=1,063), and non-Hodgkin lymphoma (N=863). Hazard ratios for the association of HIV-1 viremia and cancer risk changed after partial and full adjustment and were generally attenuated for infection-related cancers but tended to increase for infection-unrelated cancers. In the fully adjusted model, HIV-1 viremia was associated with an increased risk of Kaposi sarcoma (HR per unit increase in Log10 HIV-1 RNA viral load: 1.38, 95% CI 1.35-1.42), leukemia (HR: 1.28, 95% CI 1.13-1.45), non-Hodgkin lymphoma (HR: 1.24, 95% CI 1.19-1.29), conjunctival cancer (HR: 1.19, 95% CI 1.11-1.25), and colorectal cancer (HR: 1.11, 95% CI 1.02-1.21). Associations with other cancer types were weaker or absent.

Conclusions: Our findings underline the importance of sustained viral suppression for cancer prevention among PWH in South Africa.