Abstract Body

Background: HIV seropositive (HIV+) patients are at increased risk of squamous cell carcinoma of the anus (SCCA). Howevere, there are limited data regarding antiretroviral era survival and treatment trends for HIV+ patients with SCCA.

Methods: We used data from the Surveillance, Epidemiology, and End Results (SEER) registry linked to Medicare claims to evaluate outcomes among a cohort of male HIV+ and HIV- patients diagnosed with SCCA from 1997 to 2009. Outcomes included all-cause and anal cancer-specific mortality, colostomy placement, and SCCA recurrence. Kaplan-Meier methods were employed to compare outcomes (among the whole cohort and then stratified by cancer stage) by HIV status. We developed Cox regression models to adjust for age, race/ethnicity, modified Charlson comorbidity score, cancer stage and diagnosis year. Initial courses of treatment (surgery, radiotherapy, and chemotherapy) were also identified and compared by HIV status and SCCA stage.

Results: 1,000 male patients with incident SCCA were included in our cohort, of whom 370 were HIV+. When compared to HIV- patients, HIV+ subjects were younger (median age 48, p<0.05), had lower comorbidity scores (p <0.05), and were diagnosed with earlier stage cancers (p=0.03). Median survival in HIV+ SCCA patients ranged from 95 months (95% CI: 79 – 125) for stage 1 to 23 months (95% CI: 10 – 56) for stage IV. For early stage SCCA, we observed no difference in the pathologic depth of carcinoma invasion by HIV status (p=0.5). However, initial treatment varied by HIV status and SCCA stage (Table 1). In adjusted analyses, HIV patients had worse overall survival (HR 1.5, %CI: 1.2 – 2.0), but no difference in anal cancer-specific survival, colostomy placement or cancer recurrence.

Conclusions: In our population-based cohort, we found that HIV+ patients with SCCA presented with earlier stage cancers (possibly related to anal cancer screening) and had worse overall survival than HIV- patients. SCCA-specific survival did not differ by HIV status despite discordance in initial treatment, suggesting that overall survival differences were related to HIV-related sources of mortality.