Phase II Study of Different Doses of Radiotherapy Combined With Sintilimab in the Treatment of Locally Advanced Esophageal Squamous Cell Carcinoma

* ≥18 years old

* Histopathological examination of the primary biopsy confirmed the diagnosis of locally advanced esophageal squamous cell carcinoma

* At least one measurable lesion

* Eastern cooperative oncology group (ECOG) performance status of 0 to 1

* With adequate organs function

* Patients with active malignancy within 5 years other than the tumor studied in this study or a localized tumor that has been cured such as resected basal or squamous cell carcinoma, superficial bladder cancer, cervical carcinoma in situ, or breast cancer

* Patients who have a higher risk of bleeding or perforation due to the tumor\'s obvious invasion of the adjacent organs (aorta or trachea) of the esophageal lesion, or patients who have formed a fistula

* Patients who have received any anti-tumor therapy for the research disease in the past, including radiotherapy, chemotherapy, immunotherapy (including but not limited to interleukin, interferon, thymus hormone) and traditional Chinese medicine therapy