Adjuvant Radiotherapy is Safe and Effective for Patients with T1b-SM2 Esophageal Carcinoma After Endoscopic Resection – A Second Analysis From a Pilot Study

Abstract

Radiotherapy or Surgery is recommended for patients with T1b esophageal carcinoma (EC) after endoscopic resection (ER). T1b lesions invading the submucosa to a depth of more than 200 μm (SM2) possess higher metastatic risks. But few studies reported results of radiotherapy for this cohort. Herein, we evaluated the safety and efficacy of adjuvant radiotherapy for T1b-SM2 EC after ER.This study was a second analysis based on a piolet study where adjuvant IMRT (50-60 Gy in 25-30 fractions) with or without chemotherapy was carried out, from July 2011 to April 2019, for 31 stage-T1 EC patients with high risk factors including submucosal or lymphovascular invasion based on endoscopically resected specimen. Of the 31 subjects, patients with T1b-SM2 disease were included in the present study. The common acute toxicities, dysphagia at last follow-up, local control rate (LCR), failure pattern, overall survival (OS) and disease-free survival (DFS) were analyzed.Twenty-four out of the 31 patients were included. There were 19 (79.2%) males and 5 (20.8%) females. The median age was 62.0 (49.0-78.0) years old. Twenty-three (95.8%) patients were squamous cell carcinoma, and one (4.2%) was adenosquamous carcinoma. The number of patients with tumor of high, moderate, moderate-poor and poor differentiation were 2 (8.0%), 12 (48.0%), 3 (12.0%) and 8 (32.0%), respectively. Ten (41.7%) patients were diagnosed with lymphovascular invasion. The median invasion depth was 675.0 (230.0-1550.0) μm. After complete endoscopic submucosal dissection, all patients finished adjuvant radiotherapy as schedule, except one received 44 Gy due to refusal. Five patients (20.8%) received chemotherapy concurrently with radiotherapy. The common acute toxicities included esophagitis (Grade 1-2, 66.7%; Grade 3, 16.7%), radiation pneumonitis (Grade 1, 50.0%), leucopenia (Grade 1-2, 50.0%), and thrombocytopenia (Grade 1-2, 8.3%). No Grade 4-5 acute toxicities were observed. The median follow-up time was 35.5 (95% CI, 27.6-43.3) months. At the last follow-up, 20 (83.3%) patients were able to eat regular diet and only one (4.2%) needed liquid diet. The LCR was 100.0%. Relapse was found in two patients (8.3%), who were all synchronously with distant metastasis and regional lymph node recurrence. The invasion depth was 1300μm and 1400 μm, respectively. The two patients both received radiotherapy alone without chemotherapy. The 1-, 3- and 5-year OS were 100.0%, 87.4%, and 75.0%, respectively. And the 1-, 3- and 5-year DFS were 100.0%, 90.2% and 77.3%, respectively. The median OS and DFS were not reached. No independent prognostic factor was found for OS and DFS.Adjuvant radiotherapy is a safe and efficient supplement treatment for patients with T1b-SM2 EC after ER. For patients with ultra-deep invasion depth, adjuvant chemoradiotherapy or more aggressive treatment may be more reasonable.