Chemoradiotherapy versus radiotherapy alone in the management of early-stage anal squamous cell carcinoma: A comparative analysis of the French cohort FFCD-ANABASE.

ABSTRACT

INTRODUCTION: Early-stage anal squamous cell carcinomas (ASCC) are usually treated with chemoradiotherapy (CRT), with good outcomes. Radiotherapy (RT) alone might be sufficient while reducing toxicity. METHODS: Patients included in the French prospective FFCD-ANABASE and treated for T1-2N0 ASCC between 2015/01 and 2020/04 were divided into CRT and RT groups. Clinical outcomes and toxicity were reported. Propensity score matching was conducted for 105 pairs of patients. RESULTS: 440 patients were analyzed 261 (59.3 %) in the CRT group and 179 (40.7 %) in the RT group. The median follow-up was 35.7 months. Patients receiving CRT were younger, had better Performance Status (PS) and larger tumors. No statistical difference was observed for 3-year Disease-free survival (85.3 % vs 83 %, p = 0.28), Overall survival (89.6 % vs 94.8 %, p = 0.69) and Colostomy-free survival (84.5 % vs 87.2 %, p = 0.84) between CRT and RT groups, respectively. Propensity score-matched analysis confirmed these findings. Treatment interruptions were significantly more frequent in the CRT group (36.3 % vs 21.9 %, p = 0.0013), resulting in an Overall Treatment Time (OTT) extended by 7 days. Grade 3 CTCAE v4.0 toxicities were more prevalent in the CRT group (46 % vs 19 %, p < 0.001). CONCLUSION: Adding chemotherapy to radiotherapy did not significantly improve outcomes for T1-2N0 ASCC in our study, but increased toxicity and OTT.