Is ENI Necessary For Patients With Thoracic Esophageal Cancer After Esophagectomy And With Pathological Stage Of T1-2,N+,M0

Inclusion Criteria: 1. Age ≥ 18 and ≤70 2. ECOG performance status 0-1 3. Weight is not less than 90% of it before operation 4. Registration within 8 weeks after esophagectomy 5. Histologically proven primary thoracic esophageal squamous cell carcinoma 6. R0 resection and number of lymph nodes dissected ≥15 after esophagectomy 7. Stage T1-2N1-3M0 based pathological diagnosis 8. Chest and abdominal contrast enhanced CT within 6 weeks prior to registration(PET/CT scan is selective) 9. Without supraclavicular nodes and abdominal regions nodes existed after surgery 10. Without neo-adjuvant chemotherapy and radiotherapy 11. WBC≥ 4.0X109/L ,Absolute neutrophil count (ANC) ≥ 2.0X109/L 12. Platelets ≥ 100X109/L 13. Hemoglobin ≥ 90g/L(without blood transfusion) 14. AST (SGOT)/ALT (SGPT) ≤ 2.5 x upper limit of normal, Bilirubin ≤ 1.5 x upper limit of normal 15. Creatinine ≤ 1.5 x upper limit of normal 16. Sign study-specific informed consent prior to study entry Exclusion Criteria: 1. Multiple primary esophageal tumors 2. Prior invasive malignancy (except non-melanomatous skin cancer) unless disease free for a minimum of 2 years (For example, carcinoma in situ of the breast, oral cavity, or cervix are all permissible). 3. Severe, active comorbidity, defined as follows: 3.1 Unstable angina and/or congestive heart failure requiring hospitalization within the last 3 months 3.2 Transmural myocardial infarction within the last 6 months 3.3 Acute bacterial or fungal infection requiring intravenous antibiotics at the time of registration 3.4 Chronic obstructive pulmonary disease exacerbation or other respiratory illness requiring hospitalization or precluding study therapy at the time of registration 3.5 Acquired immune deficiency syndrome (AIDS) based upon current CDC definition; note, however, that HIV testing is not required for entry into this protocol. The need to exclude patients with AIDS from this protocol is necessary because the treatments involved in this protocol may be significantly immunosuppressive. 4. Pregnancy or women of childbearing potential and men who are sexually active and not willing/able to use medically acceptable forms of contraception. 5. Prior systemic chemotherapy, prior radiation therapy or prior target drug therapy