Comparison of intravenous 5-Fluorouracil with Oral Capecitabine in the Treatment of Anal Squamous Cell Carcinoma Using Modern Radiation Techniques

Background: Anal squamous cell carcinoma (ASqCC) is a rare malignancy, traditionally treated with combined chemoradiation, with a continuous infusion of 5-fluorouracil (5-FU) and mitomycin C (MMC). Replacing intravenous (IV) 5-FU with oral capecitabine (oral fluoropyrimidine) has been reported as a non-inferior treatment option. However, these data are scarce, with variable results. Objectives: To examine the outcome of patients with ASqCC treated with either IV 5-FU or capecitabine concomitantly with radiation therapy. To compare treatment side effects, local recurrence, and general outcome. Methods: We reviewed charts of patients who were diagnosed with stage l-lll ASqCC. All participating patients received chemoradiation at the Assuta Medical Center between 2011 and 2019. Results: In this study, 43 patients with ASqCC were eligible; 14 received 5-FU and 29 were treated with capecitabine. Basic characteristics were similar between the two groups, with longer follow-up for the 5-FU group. Six months following treatment, 100% (13/13 with adequate follow-up) of the 5-FU group had complete clinical response, compared to 84% in the capecitabine group (21/24), P= 0.143. The local recurrence incidence was higher in the 5-FU group at 23% (7,10,26 months following therapy, and none in the capecitabine group (P = 0.088). Although local and hematological toxicities were similar between groups, one patient receiving capecitabine died during chemoradiotherapy. Conclusions: Oral capecitabine demonstrated non-inferior disease control in ASqCC treated with chemoradiotherapy. We recommend oral capecitabine over continuous IV 5-FU in locally and locally advanced ASqCC. Close monitoring of side effects is required to reduce major toxicity.