Re-irradiation of In- or Out-of-PTV Esophageal Recurrence after Definitive Chemoradiotherapy for Esophageal Squamous Cell Carcinoma

Abstract PURPOSE To compare the clinical characteristics, toxicity and efficacy of re-irradiation between locoregional esophageal recurrence within and outside the initial PTV (Planning target volume) after definitive chemoradiotherapy for ESCC (esophageal squamous cell carcinoma). MATERIALS AND METHODS Patients receiving re-irradiation for esophageal recurrence three months after definitive chemoradiotherapy for ESCC were retrospectively analyzed. Patients were divided into in- and out-of-PTV recurrence groups depending on the recurrent lesion center within or outside the initial PTV. The clinical characteristics, toxicities and efficacy of re-irradiation were compared between these two groups. RESULTS 116 eligible patients from June 2009 to October 2019 were analyzed with 68 patients in the in-PTV group and 48 in the out-of-PTV group. The median initial radiation dose was 61.2 Gy in both groups. 39 patients (57.4%) in the in-PTV group and 28 patients (58.3%) in the out-of-PTV group received chemoradiotherapy in salvage treatment, while the others received re-irradiation only. The median re-irradiation doses were 50.4 Gy and 60 Gy in the in- and out-of-PTV groups, respectively. The median survival times were 9.9 months and 31.8 months in the in-PTV and out-of-PTV groups ( P < 0.001), respectively, with 2-year local control rates 10.7% and 56.9% ( P < 0.001). The rates of esophageal perforation in the in-PTV and out-of-PTV groups were 8.8% and 4.2% during or after re-irradiation, respectively, with esophageal hemorrhage (≥ grade 3) 11.8% and 0%. CONCLUSION Patients with out-of-PTV esophageal recurrence are different from in-PTV recurrence with the better safety, radiosensitivity and efficacy of re-irradiation after definitive chemoradiotherapy.