Radiotherapy with S-1 for the treatment of esophageal squamous cell carcinoma 75 years or older

ObjectiveExplore the efficacy and safety of involved-field irradiation (IFI) combined with S-1 as definitive concurrent chemoradiotherapy (dCRT) for locally advanced elderly esophageal squamous cell carcinoma (ESCC), under the premise of intensity-modulated radiotherapy (IMRT).MethodsWe designed a prospective single-arm phase II study. The study enrolled 91 patients aged 75 to 92 years. Eligible participants had histologically confirmed squamous cell carcinoma, stage II to IV disease based on the 8th edition of the American Joint Committee on Cancer (AJCC). All elderly patients (EPs) received dCRT with S-1. which was administered orally twice daily for 28 days. The radiotherapy dose was 61.2 Gy delivered in 34 fractions or 50.4 Gy delivered in 28 fractions. The primary endpoint was 2-year overall survival (OS), and the secondary endpoints were progression-free survival (PFS), local control rate (LCR), and safety.ResultsFrom July 2017 to July 2021, we enrolled EPs with ESCC who were treated at the Jiangsu Cancer hospital. As of August 1, 2023, the median follow-up of surviving EPs was 31.4 months (IQR: 25.2 to 72.6 months). 83 patients (91.2%) completed the whole course of treatment. The 2-year OS rate was 59.2%, and the PFS rate was 43.7%. The most common grade 1 to 2 adverse effects (AEs) were radiation esophagitis (79.1%), and then were radiation pneumonia (46.2%). Anemia (41.8%) was the most common of grade 1 to 2 hematologic toxicity. The incidence of grade 3 or above AEs was 24.2%, and the incidence of leukopenia was the highest (11.0%). There was not one death due to treatment-related toxicity. In a subgroup analysis of radiotherapy doses, we found no statistically significant differences in PFS (P = 0.465) and OS (P = 0.345) in EPs with ESCC who received 50.4 Gy and 61.2 Gy, and that patients in the 50.4 Gy group had lower dermatitis (P = 0.045) and anemia (P = 0.004).ConclusionsIF-IMRT combined with S-1 is a promising regimen for elderly ESCC. And the radiotherapy dose of 50.4 Gy remains the standard dose for EPs with ESCC undergoing CCRT.