The primary objective is to compare PD-1 inhibitor combined with preoperative chemoradiotherapy followed by surgery versus neo-adjuvant chemoradiotherapy followed by surgery, in terms of the overall survival time (OS) in patients with Stage T1-4aN1-3M0 or T3-4aN0M0 squamous cell esophageal carcinoma.

Inclusion Criteria:

1. Histologic diagnosis of squamous cell thoracic esophageal carcinoma of Stage T1-4aN1-3M0 or T3-4aN0M0,which is potentially resectable.
2. Patients must not have received any prior anticancer therapy.
3. More than 6 months of expected survival.
4. Age ranges from 18 to 70 years.
5. Absolute white blood cells count ≥4.0×109/L, neutrophil ≥1.5×109/L, platelets ≥100.0×109/L, hemoglobin ≥90g/L, and normal functions of liver and kidney.
6. WHO PS score 0-1
7. Signed informed consent document on file.

Exclusion Criteria:

1. Patients have received any prior anticancer therapy.
2. Patients are diagnosed or suspected to be allergic to sintilimab,toxal or cisplatin.
3. Patients with concomitant hemorrhagic disease.
4. Patients who cannot tolerate surgery.
5. Pregnant or breast feeding.
6. Patients without informed consent because of psychological, family, social or any other factors.
7. Patients with concomitant peripheral neuropathy, whose CTC status is 2 or even more.
8. Patients with malignant tumors other than esophageal cancer,except for non-melanoma skin cancer, in situ cervical cancer, or cured early prostate cancer.
9. Patients with history of diabetes over 10 years and unsatisfactory glycemic control.
10. Patients with severe heart,lung,liver,renal dysfunction, hematopoietic system diseases, immune system diseases, cachexia or other diseases that lead to intolerance of chemoradiotherapy or surgery.
11. Patients with history of autoimmune diseases, immunodeficiency, or organ and allogeneic bone marrow transplantation.
12. Patients with history of interstitial lung disease or noninfectious pneumonia.
13. Patients with active pulmonary tuberculosis infection, or a history of active pulmonary tuberculosis infection within one year before enrollment, or a history of active pulmonary tuberculosis infection more than one year ago without regular treatment.
14. Patients with active hepatitis B ( HBV DNA ≥ 2000 IU / mL or 104 copies / mL ) or hepatitis C ( HCV antibody positive ).