Fraction Dose Escalation of Split-course Hypofractionated Concurrent Chemoradiotherapy Following Induction Chemo-immunotherapy in Unresectable Locally Advanced Esophageal Squamous Carcinoma: a Phase I Study.

Inclusion Criteria: * histologically confirmed ESCC * II-IVB stages (IVB stage only with metastatic celiac or supraclavicular lymph nodes) based on the TNM staging system proposed by the International Union Against Cancer (UICC 2002) * Eastern Cooperative Oncology Group (ECOG) performance status score 0-1 * Charlson Comorbidity Index score≤4 * oral medication can be administered despite esophageal obstruction * adequate hematological, renal and hepatic functions Exclusion Criteria: * contraindication for radiotherapy or chemotherapy * prior malignancies, except for curable non-melanoma skin cancer or cervical carcinoma in situ * distant metastasis, except for celiac or supraclavicular lymph nodes metastases