Anal cancer occurs earlier in HIV-positive individuals (mean age 37 years) compared with HIV-negative men (58 years) and HIV-negative women (65 years). This difference of two decades in age of onset supports the hypothesis that the biology of SCCA differs between HIV-positive and HIV-negative patients [5]. The effect of HIV infection on the natural history of anal HPV infection is poorly understood, but most experts agree on two points: 1) 95% of HIV-positive homosexual men are co-infected with HPV; and 2) HIV infection favors persistence of HPV infection within the ano-genital tract (uterine cervix, vagina, and anal canal).