Evaluating the Optimal Re-irradiation Dose for Locally Recurrent Esophageal Squamous Cell Carcinoma After Definitive Radiotherapy

Background: Re-irradiation (re-RT) has the active effect of relieving clinical symptoms and prolonging the survival of patients with recurrent esophageal squamous cell carcinoma (ESCC). However, the optimal re-RT dose is still uncertain. Here, we analyzed the prognostic factors associated with survival and explored the optimal re-RT dose for patients with recurrent ESCC following definitive radiotherapy.

Patients And Methods: The data of 47 patients with recurrent ESCC who were retreated between 2010 and 2014 were retrospectively analyzed. All patients received a radiation dose > 50 Gy during the primary treatment. The median time to recurrence after primary radiotherapy was 26 months (range 6-120 months). All patients had in-field recurrence in the esophagus. Recurrence within the local site was observed in 37 patients (78.7%), and recurrence in both the local site and regional nodes were observed in 10 patients (21.3%). All patients received 3D conformal re-RT with a median dose of 58 Gy (range 26-64 Gy). Chemotherapy was sequentially used in 27.7% of the patients. Survival curves were constructed according to the Kaplan-Meier method and were compared by log-rank tests. The factors predictive of survival were identified with univariate and multivariate analyses.

Results: Dysphagia relief after re-RT was achieved in 20 of the 35 symptomatic patients (57.1%). The median survival time (MST) of all patients was 17 months, and the 1-, 2-, 3- and 5-year overall survival (OS) rates were 72.3, 25.5, 17.0 and 2.1%, respectively. In the univariate analysis, an Eastern Cooperative Oncology Group Performance Status (ECOG-PS) of 0-1 (P = 0.014), recurrence at the local site (P = 0.048), time to recurrence ≥24 months (P = 0.006) and re-RT dose ≥50 Gy (P < 0.001) were associated with favorable OS. In the multivariate analysis, only re-RT dose was an independent factor for OS (P = 0.007). Severe complications were observed in 7 patients, two of whom received a re-RT dose > 60 Gy.

Conclusion: Our results demonstrated that patients with recurrent ESCC following definitive radiotherapy had unfavorable OS. Re-RT could be considered a feasible and effective treatment modality. A re-RT dose > 50 Gy could improve the survival outcomes, and a dose > 60 Gy should be administered with caution due to the risk of severe complications.