Résumé
Early-stage node negative anal squamous cell carcinoma (ASCC) present good outcomes and are usually treated by concomitant chemoradiotherapy (CRT) according to international guidelines. Radiotherapy (RT) alone might be sufficient to control disease whileavoiding toxicity due to chemotherapy. This study aims to assess clinical outcomes, prognostic and toxicity between CRT and RT for patients with T1-2N0 ASCC included in the French FFCD-ANABASE cohort.Material and methods: patients treated for T1-2N0 ASCC between 2015/01 and 2020/04 were divided in two groups: CRT and RT alone. Primary endpoint was 3-year Disease-Free Survival (DFS). Secondary endpoints included Overall Survival (OS), Colostomy-Free Survival (CFS) and toxicity. A propensity score was performed and matched 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, presented a better Performance Status (PS) and had larger tumor size. There was no statistical difference for 3-year DFS (85.3% vs 83%, p=0.28), OS (89.6% vs 94.8%, p=0.69) and CFS (84.5% vs 87.2%, p=0.84) between CRT and RT group, respectively. Analyses on the matched set confirmed the results. Treatment interruptions were statistically more important in the CRT group (36.3% vs 21.9%, p=0.0013), with an Overall Treatment Time (OTT) extended by 7 days. Grade 3 CTCAE v4.0toxicities were more important in the CRT group (46% vs 19%, p<0.001).Conclusion: adding chemotherapy to radiotherapy doesn’t significantly improve outcomes for localized early-stage ASCC in our study. It was associated with more toxicity and increased overall treatment time.