Efficacy and Safety of Chemoradiation with Cisplatin plus Capecitabine in Localized Squamous Cell Anal Cancer

Background Localized Squamous Cell Anal Cancer (SCCAC) is a rare disease. The standard of care treatment with curative intent is chemoradiation (CRT) with mitomycin (MMC) or cisplatin (CDDP) plus infusional 5-Fluoracil (5-FU). Capecitabine may replace 5-FU in MMC doublet. However, MMC and infusional pumps are frequently unavailable in underdeveloped countries. CCDP and capecitabine are widely available, but there is no prospective data about the feasibility and efficacy of this combination in a definitive SCCAC CRT setting. Methods A Prospective cohort study aimed to evaluate the safety and efficacy of treatment with chemoradiation with CDDP 60mg/m2 D1 and D29 plus Capecitabine 825mg/m2 BID in a population without MMC and infusional pump access. Eligible patients (pts) had T2-4, N0-3, and M0 disease candidates for a full curative CRT regimen. The study data were prospectively collected using REDCap. The primary endpoint was the response by RECIST v.1.1 at 24 weeks(w). The secondary endpoints included toxicity by CTCAE v.5.0, PFS, and OS. Results We enrolled 40 consecutive pts between Aug/2019-Dec/2022 in a tertiary cancer center in Brazil. The median age was 61.6y, the majority were stage III (n = 31, 77.5%) and ECOG 1 (n = 20, 50%). HIV + serology was observed in 11 pts (27,5%). All patients received CRT, with a median dose of 54Gy in the primary tumor and 45Gy in the elective nodes. At 8w, 35% (n = 14) had a complete response (CR), 50% (n = 20) partial response (PR), and 2.5% (n = 1) progressive disease (PD). Considering the 35 participants evaluable for response at 24 weeks months by RECIST v.1.1, the disease control rate was 88.5% (n = 31). CR was observed in 47,5% (n = 19), PR in 20% (n = 8), and PD in 12,5% (n = 5). 11 pts had disease recurrence, and six died. The 1y estimated OS was 94.7% (IC95%: 80.7–98.6%), and 1y estimated PFS was 75.3% (IC95%:57.8–86.3%). Colostomy-free survival at one year was 89.6% (IC95%: 74.7–95.9%). Regarding toxicities, any grade 3/4 toxicity was present in 45% (n = 18) being the main G3/4 clinical toxicity radiodermatitis. Conclusions The CRT regimen with C + CDDP represents an alternative treatment for localized anal canal tumors in a population that does not have access to MMC and 5-FU infusion pumps. Further studies in this population are encouraged to confirm these findings.