Predicting Postoperative Chemotherapy Efficacy in Patients With Esophageal Squamous Cell Carcinoma

Esophageal cancer remains a disease with a poor prognosis. Chemotherapy is an important part of its treatment, but there are cases in which chemotherapy is ineffective. The investigators aim to develop a model to predict the response to chemotherapy by DNA methylation of preoperative biopsy specimens to identify the chemotherapy ineffective group.

Inclusion Criteria: 1. Patients who had histologically confirmed esophageal squamous cell carcinoma. 2. Patients who had undergone chemotherapy. 3. Patients receiving initial chemotherapy 4. Written informed consent following full study information is provided to the patient. Exclusion Criteria: 1. Patients for whom a preoperative biopsy sample cannot be obtained 2. Patients who cannot assess at 2 months later after chemotherapy. 3. Patients with multiple cancers.