Dynamic ctDNA Monitoring in Neoadjuvant Therapy for Esophageal Squamous Cell Carcinoma

Inclusion Criteria:

1. Age between 18 and 70 years, regardless of gender.
2. Patients with histologically confirmed clinical stage II-III thoracic esophageal squamous cell carcinoma.
3. Neck enhanced CT scan showing no suspicious lymph node metastasis in the neck; no systemic metastasis detected by imaging examination.
4. Expected to achieve R0 resection.
5. ECOG performance status of 0-1.
6. No prior anti-tumor treatment for esophageal cancer, including chemotherapy, radiotherapy (including planned radiotherapy during the study period), hormone therapy, and immunotherapy.
7. Measurable lesions (according to RECIST v1.1 criteria).
8. Preoperative evaluation of organ function shows no contraindications for surgery.
9. Laboratory tests confirm good bone marrow, liver, kidney function, and coagulation function.
10. Able to provide informed consent and willing to cooperate with clinical follow-up.
11. Willing to provide peripheral blood samples for testing, as well as the patient's medical history, current treatment information, imaging studies, and tumor marker data, and willing to use the testing data for further scientific research, clinical diagnosis and treatment, and commercial product development.

Exclusion Criteria:

1. Unable to provide a sufficient amount of tissue samples/blood samples required for the study before treatment.
2. Patient refuses to undergo MRD testing.
3. History of malignancies other than esophageal cancer within the past 5 years (excluding cured localized tumors, such as cervical carcinoma in situ, basal cell carcinoma, and prostate carcinoma in situ; patients with prostate cancer who have received hormone therapy and achieved disease-free survival for more than 5 years are not excluded).
4. History of gastrointestinal bleeding within the past 6 months, or presence of coagulation abnormalities at enrollment, or currently receiving thrombolytic or anticoagulant therapy, indicating a high risk of bleeding.
5. Severe cardiovascular or cerebrovascular diseases.
6. History of interstitial lung disease or active pneumonia requiring steroid treatment at enrollment.
7. Active tuberculosis at enrollment or received anti-tuberculosis treatment within the past year.
8. Bronchial asthma requiring intermittent use of bronchodilators or other medical interventions at enrollment.
9. Presence of systemic infectious diseases requiring systemic treatment within the past 4 weeks at enrollment.
10. Severe unhealed wounds, active ulcers, or untreated fractures at enrollment.
11. Presence of other non-surgical conditions.
12. Previous surgeries that prevent the use of gastric conduit for esophageal reconstruction.
13. Severe allergic reactions to chemotherapy drugs (such as paclitaxel, albumin-bound paclitaxel, cisplatin, or carboplatin) or any monoclonal antibody.
14. History of organ transplantation.
15. Other conditions deemed unsuitable for participation in this study according to the investigator's judgment.