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Background:  We sought to determine how the availability of highly active antiretroviral therapy (HAART) influenced rates of anal cancer among AIDS patients.

Methods:  We performed a match between the AIDS and cancer registries for San Diego County. Registry data were complete from 1988 to 2000 but no cases of anal cancer were diagnosed before 1992. 

Results:  We identified 39 cases of anal squamous cell carcinoma. All were men and 38 (97%) were men who have sex with men (MSM). The median age was 42 years (range 25 to 59); 28 (72%) were white, 2 (5%) were black, 7 (18%) were Latino, and 2 (5%) were of unknown race/ethnicity. The median CD4 count was 120/MCL (range 2 to 551). Among the 36 patients diagnosed with HIV prior to or simultaneous with their anal cancer diagnoses, the median duration of known HIV infection was 78 months (range 0 to 175). The median duration of HIV infection in the pre-HAART era (1992 to 1995) was 29 months while post-HAART (1996 to 2000) it was 84 months (p = 0.01). Eight cases (21%) were diagnosed pre-HAART, while 31 (79%) were diagnosed post-HAART. The number of cases increased each year between 1996 and 2000 (3 [8%] in 1996; 4 [10%] in 1997, 5 [13%] in 1998, 8 [21%] in 1999, and 11 [28%] in 2000) despite a declining incidence of AIDS in San Diego County. Thus, the rate of anal cancer increased from 2.8 per 1000 AIDS cases in 1992 to 24.7 per 1000 in 2000 (r = 0.83, p = 0.005). Pre-HAART, 3 (38%) of 8 cases were in-situ while post-HAART, 8 (26%) of 31 were in-situ (p = 0.51). Of these 28 patients (72%) received surgical treatment, 1 (3%) received radiation therapy, 1 (3%) received chemotherapy, 16 (41%) received both, and 21 (54%) received neither. At most recent follow-up, 20 (51%) were alive. Among the 19 deceased, 6 (32%) died of HIV/AIDS, 6 (32%) died of anal cancer, and 7 (37%) died of other/unknown causes. The median survival was 37 months (range: 2-104). Data limitations include lack of information regarding HAART usage, smoking status and anal cancer rates in HIV-infected persons without AIDS and uninfected MSM in San Diego County.

Conclusions:  Cases of anal cancer among AIDS patients in San Diego County have increased since the introduction of HAART. This could be related to increased screening for anal cancer or increased longevity with the use of HAART. Fewer in-situ tumors in the post-HAART era argue against a screening phenomenon. The longer duration of HIV infection post-HAART suggests that HAART increases the time at risk for the development of anal cancer.

Keywords: Anal cancer; Antiretroviral therapy