Accelerated radiotherapy in the treatment of anal squamous cell carcinoma - a single institution retrospective evaluation.

Background: The goal of treatment for anal squamous cell carcinoma (ASCC) is to preserve a functional anal sphincter and maintain the best quality of life. Surgical excision is reserved only for very early stages, and concomitant chemoradiotherapy (CHRT) is usually used in the treatment of ASCC. The aim of the study is a retrospective analysis of a group of patients with ASCC treated with CHRT using accelerated radiotherapy at the Institute of Radiation Oncology of Bulovka University Hospital in Prague (IRO BUH).

Patients and methods: Between 2014 and 2022, 73 patients with ASCC underwent definitive CHRT. Patients were treated with accelerated radiotherapy in 25 fractions - to the tumor and affected lymph nodes at 2.3 Gy to a dose of 57.5 Gy and to the area of the lymphatics at 1.8 Gy to a dose of 45 Gy. Concomitant chemotherapy mitomycin + 5-fluorouracil, later mitomycin + capecitabine was administered.

Results: A total of 64 (87.7%) patients underwent CHRT, in the remaining 9 (12.3%) cases only radiotherapy was applied. The 2- and 5-year overall survival rates were 85.8% and 76.3%, disease-free survival 88.0% and 86.3%, local control 91.9% and 91.9%, and colostomy-free interval 68.5% and 68.5%, respectively. The median of these parameters was not reached. Acute toxicity grade G3-4 was reported in 51 (69.8%) patients, late toxicity G3-4 was detected in 10 (13.7%) cases. No grade 5 toxicity occurred.

Conclusion: Accelerated radiotherapy in the treatment of ASCC resulted in favorable disease control but was burdened with significant toxicity.