Abstract
BACKGROUND: The optimal radiation dose for treating non-metastatic superficial esophageal squamous cell carcinoma is unknown. In this retrospective observational study, we investigated the influence of radiation dose and pretreatment endoscopic prediction of tumor invasion depth on local recurrence after definitive chemoradiotherapy in patients with superficial esophageal squamous cell carcinoma. METHODS: We analyzed 134 patients with clinical Tis-T1N0M0 esophageal squamous cell carcinoma who underwent chemoradiotherapy at our institution between 2006 and 2019. Patients were grouped into standard-dose (50.0-50.4 Gy) and high-dose (60.0 Gy) radiotherapy groups. The outcomes of interest were local recurrence and major local recurrence (endoscopically unresectable local recurrent tumors). Kaplan-Meier analysis and the log-rank test were used with propensity score and inverse probability of treatment weighting. Cox proportional hazards analysis was performed to identify predictors of local recurrence and major local recurrence. RESULTS: The median follow-up times were 52 and 84 months for the standard-dose and high-dose groups, respectively. The adjusted 3-year local recurrence and major local recurrence rates in the standard-dose and high-dose groups were 33.8 and 9.6% (adjusted hazard ratio, 4.00 [95% confidence interval: 1.64-9.73]; adjusted log-rank p = 0.001) and 12.5 and 4.7% (adjusted hazard ratio, 3.13 [95% confidence interval: 0.91-10.81]; adjusted log-rank p = 0.098), respectively. Cox proportional hazards analysis showed that standard-dose radiotherapy and endoscopic findings of deep submucosal invasion are independently associated with local recurrence and major local recurrence. CONCLUSIONS: High-dose radiotherapy is more beneficial for local tumor control than standard-dose radiotherapy in patients with non-metastatic superficial esophageal squamous cell carcinoma. The use of high-dose radiotherapy may merit consideration for tumors with deep submucosal invasion.