PATIENTS WITH SQUAMOUS CELL CARCINOMA OF THE ANAL (SCCA) AND HIVINFECTION TREATED WITH DEFINITIVE CHEMORADIOTHERAPY (CHRT): A MULTINATIONAL RETROSPECTIVE COMPARATIVE STUDY

Introduction: The definitive treatment for localized SCCA is ChRT in combination with infusional 5-FU. A meta-analysis of published studies from the past decades conducted by our group showed significantly higher dermatological and hematological toxicity and rates of disease-free survival and overall survival at three years significantly lower in HIV-positive patients (pts). We aimed to compare treatment outcomes between HIV-negative and positive pts, (all under antiretroviral therapy) according to the chemotherapy regimen (Nigro versus ACT-II) and treated in the recent years. Methods: Retrospective multinational comparative cohort of consecutive pts with histological diagnosis of SCCA and localized disease who received definitive ChRT. The primary endpoint was complete response (CR) rate defined by absence of clinical and radiological evidence of disease at 6 months. Second endpoint was DFS rate in 3 years, time to achieve CR, and prognostic factors of improved outcomes. Results: A total of 185 patients with SCCA were included: 43 (23.2%) were HIV-positive and 142 (76.8%) were HIV-negative. HIV-positive pts were more commonly men: 28 (65.1%) vs 27 (19%) (p < 0.001) and had clinical stage III: 27 (62.8%) vs 75 (52.8%) (p = 0.249). The overall CR rate was 67.4% vs 91.5% for HIV-positive and negative pts, respectively (P < 0.001). Among pts who achieved a CR (N = 159), the rates of CR for HIV-positive vs negative pts were, respectively: 27.9% vs 82.4% at 6 months and 39.5% vs 9.2% after 6 months post ChRT (p < 0.001).The overall CR rates of HIV-positive pts were 50% (6 out of 12) with ACT2 and 69.5% (16 out of 23) with Nigro. For HIV-negative, the CR rates were 92.5% (37 out of 40) for ACT2 and 91.4 % (75 out of 82) for Nigro. The rate of colostomy was higher in the HIV + group 23.2% vs 16,1% in the HIV negative (p = 0.199). In a median follow-up of 47.8 months the time to achieve CR was 7.8 (95% CI:5.7-10) months for HIVpositive vs 4.8 95% (CI:4.54-5.25) months for negative HIV, (p < 0.001). The DFS rate at 36 months was 61% and 78% for HIV-positive and HIV-negative, respectively (p = 0.023). Conclusions: HIV-positive pts treated with more modern regimens had inferior DFS, higher rates of colostomy and delayed CR. While HIV-negative pts present similar outcomes with Nigro or ACT2 regimen, our data suggest that HIV-positive pts present inferior outcomes ACT2.