Radiotherapy dose may not affect prognosis in ESCC patients receiving first-line chemoradiotherapy-immunotherapy: A multicenter retrospective study.

Combined immunotherapy based on radiotherapy and chemotherapy is increasingly widely applied in clinical practice for patients with non-surgical treatment of esophageal cancer. However, radiotherapy doses in triple combination therapy have not received much attention. Therefore, a retrospective, non-interventional, real-world study of patients with esophageal squamous cell carcinoma (ESCC) was conducted. The primary objective was to assess whether radiotherapy dose is a determining factor in the prognosis of ESCC patients in a triple therapy. A total of 1283 ESCC patients receiving triple therapy were collected from 7 cancer centers in China between January 2019 and December 2022. Among them, 299 ESCC patients receiving the first-line triple therapy were eligible for enrollment. Due to different radiotherapy doses, patients were classified into a high-dose (HD) group at 60Gy and a low-dose (LD) group at 50.4Gy. Propensity Score Matching (PSM) analysis was conducted to compare and analyze differences in outcomes, toxicity, and failure patterns between the two groups. Further subgroup analysis was performed to identify the individual population. Of the 299 ESCC patients eligible for enrollment, 198 (66.2%) were in the HD group and 101 (33.8%) were in the LD group. After PSM, there were 93 patients in each group. The median follow-up time was 25.5 months (95CI: 18.6-32.4). The median overall survival (mOS) and median progression-free survival (mPFS) in the LD group were 31.3 months (95%CI: 16.5-46.2) and 17.0 months (95%CI: 15.1-19.0), respectively. The mOS and mPFS in the HD group were 28.5 months (95%CI: 16.1-40.9) and 20.6 months (95%CI: 13.5-27.8), respectively. There was no statistically significant difference between the HD group and the LD group (X2 = 0.057, 0.974, P = 0.811, 0.324). The disease control rates of LD and HD groups were 89.2% and 90.3% respectively, and the difference was not statistically significant (X2 = 0.059, P = 0.809). In the LD group, 35 cases (37.6%) had distant metastasis and 21 cases (22.6%) had local recurrence. In the HD group, 32 cases (34.4%) had distant metastasis and 14 cases (15.1%) had local recurrence. There were no statistically significant differences between the HD group and the LD group (X2 = 1.725, 0.210, P = 0.189, 0.647). Multicenter data from China showed that higher radiotherapy doses provide no survival benefit for ESCC patients receiving first-line triple therapy.