Clinical outcomes of definitive radiotherapy for patients with cT1aN0M0 esophageal cancer unsuitable for endoscopic resection and surgery.

Background: Studies on the clinical outcomes of radiotherapy for clinical (c)T1aN0M0 ( Methods: Patients with cT1aN0M0 esophageal squamous cell carcinoma who underwent definitive RT or CRT between January 2009 and December 2020 were retrospectively reviewed. The initial response, toxicities, survival rates, recurrence patterns, and salvage treatments of the patients were evaluated. Initial response was measured using the Response Evaluation Criteria in Solid Tumors guideline. Toxicity was assessed and documented following the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Survival rates from the date of initiation of treatment were measured using the Kaplan-Meier method. Results: Twenty patients treated with definitive RT or CRT were included in the study. The median follow-up duration was 55 months (range, 13-131 months). All patients achieved complete response to the initial treatment. Grade 3 acute toxicities observed esophagitis (10%), pneumonitis (5%), and leukopenia (5%). Late toxicities higher than grade 3 were not observed. The 1-, 3-, and 5-year overall and disease-specific survival rates were 100% and 100%, 83% and 100%, and 67% and 100%, respectively. No treatment-related deaths occurred. Among the 20 patients, 6 showed local recurrence and 2 showed metachronous recurrence. Seven patients underwent salvage endoscopic submucosal dissection (ESD), and one underwent argon plasma coagulation treatment. After the endoscopic treatment, no recurrences were observed. Conclusions: Definitive RT or CRT was considered an alternative initial treatment for patients with cT1aN0M0 EC who were unsuitable for endoscopic resection and surgery.