Cisplatin and capecitabine as definitive chemoradiation for squamous cell carcinoma of the anal canal (SCCAC): A prospective cohort.

e15503 Background: 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, adherence, 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 61y, 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). At 6 months, CR was observed in 55% (n = 22), PR in 22.5% (n = 9), and PD in 10% (n = 4). 11 pts had disease recurrence, and six died. 1y OS was 94.7% (IC95%: 80.7- 98.6%), and 1y PFS was 75.3% (IC95%:57.8 - 86.3%). Colostomy-free survival at one year was 89.6% (IC95%: 74.7 - 95.9%). Median PFS and OS were not reached with a 2-year median follow-up. Regarding toxicities, radiodermatitis was observed in 94% (n = 36), nausea in 90% (n = 36), and diarrhea in 65% (n = 26). Any grade 3/4 toxicity was present in 27.5% (n = 11), being the majority of radiodermatitis. Four older pts (average age 73y) had definitive suspension of treatment due to toxicity, 06 pts were hospitalized because of a skin infection, and one died due to treatment toxicity. Conclusions: Definitive chemoradiotherapy with cisplatin and capecitabine is feasible; however, older populations require extra attention to early toxicities management.