Background: Recent studies have shown that the incidence of squamous cell cancer of the anus (SCCA) has increased in the combined antiretroviral therapy (cART) era. The effect of undetectable HIV viral loads as a result of successful cART has not been evaluated.
Methods: We performed a retrospective cohort study among male US veterans diagnosed with HIV and followed between 1985 and 2009 using the Veterans Affairs Immunologic Case Registry (VA-ICR). We calculated age-adjusted incidence rates and rate ratios for SCCA. We conducted Cox proportional hazards ratios of SCCA in a multivariable model including time-varying covariates of nadir CD4 count and overall percentage of time with an undetectable HIV viral load.
Results: The age-adjusted SCCA incidence rate among the group who ever received cART was 146.8/100,000 person-years (95% confidence interval, 124.1 to 172.6) and was not significantly higher than the SCCA rate of those who never received cART (134.3/100,000 person-years; 95% confidence interval, 112.5 to 159.0). In a multivariable model limited to veterans who had ever received cART (adjusted for demographic variables, nadir, and most recent CD4 counts) individuals who had 61%–80% or 81%–100% of follow-up time with undetectable HIV viral loads had significantly decreased SCCA risk compared with those who had undetectable HIV viral loads <20% of the time (odds ratio, 0.56; P = 0.040 and odds ratio, 0.55; P = 0.0004, respectively).
Conclusions: HIV control as measured by the percent of time with undetectable HIV viral load seems to decrease the risk of SCCA. Optimizing cART adherence and HIV viral load control may decrease the risk of subsequent SCCA.