The purpose of this study is to observe and evaluate the correlation between ctDNA-MRD and the therapeutic effect and prognosis of stage II-IVA operable esophageal squamous cell carcinoma.

ESCC patients with II-IVA resection will undergo MRD examination at the following time: the first examination is before the operation, the second examination is 7-10 days after the operation, and then 1 month after the operation, 2 weeks after the end of adjuvant treatment (if available), the follow-up period (every 3 months if there is no postoperative treatment) and the progress (the progress of the disease confirmed by the researcher), the patients will receive close MRD monitoring to evaluate the correlation between ctDNA-MRD and therapeutic efficacy and prognosis.

Inclusion Criteria:

1. Patients with stage II-IVA Esophageal squamous cell carcinoma confirmed by clinical pathological staging;
2. ≥18 years;
3. Eastern Cooperative Oncology Group performance status score (ECOG PS) is 0 ~ 1 points;
4. Expected survival time ≥ 6 months;
5. Patients agree and have the ability to follow the planned study visits, laboratory tests and other research steps.

Exclusion Criteria:

1. Patients with other malignant tumors;
2. Patient had undergone surgery before admission;
3. Pregnant or lactating women;
4. Patients with other serious diseases;
5. Patients who could not understand the experiment content and could not cooperate with them and refused to sign the informed consent form;
6. Patients with contraindications to radiotherapy and chemotherapy;
7. Other researchers think it is not suitable.

Esophageal squamous cell carcinoma patients who were initially diagnosed as stage II-IVA (TNM V8) and planned to undergo radical surgery