The aim of this study was to detect the whole genome hydroxymethylation of peripheral blood ct DNA in normal population, patients with p0~pI esophageal squamous cell carcinoma and pII~pIV esophageal squamous cell carcinoma by using DNA methylation detection technology. To compare the differences in genomic methylation levels between different groups, to find out the methylolation site system associated with early esophageal squamous cell carcinoma, and to verify the genes related to esophageal squamous cell carcinoma by ctDNA methylolation. Application of basicization in early screening of esophageal squamous cell carcinoma.

The aim of this study was to detect the whole genome hydroxymethylation of peripheral blood ct DNA in normal population, patients with p0~pI esophageal squamous cell carcinoma and pII~pIV esophageal squamous cell carcinoma by using DNA methylation detection technology. The differences in genomic methylation levels between different groups were compared to identify the methylolation site system associated with early esophageal squamous cell carcinoma. Then, using the genomic methylolation technique, 5hmC-DNA enrichment was performed on the peripheral venous blood samples of the experimental group before surgery and the peripheral venous blood samples of the control group, respectively, and then the high abundance and high significance were selected. The 5hmC-DNA fragment was verified by PCR amplification. The genes related to esophageal squamous cell carcinoma were verified by ctDNA methylolation. Finally, the methylolation genes related to esophageal squamous cell carcinoma were identified, and the application of DNA methylation in early screening of esophageal squamous cell carcinoma was explored.

Inclusion Criteria:

1. Diagnosis of esophageal squamous cell carcinoma by pathological cytology and histology.
2. Clinically judged patients with p0~pIV initial treatment.（1 Variable risk factors are overeating food (habits) and family history. 2 Among all the patients, the ratio of male to female is 3:1, and the age is between 50 and 70 years old. In addition to eating too hot food, other eating habits (such as eating fresh fruits and vegetables, eating preserved food, etc.) are consistent, other factors (such as BMI, smoking, drinking, etc.) as much as possible. 3 In order to rule out the interference of other diseases, each sample needs to be determined to have no history of other diseases (such as neurodegenerative diseases, leukemia).）
3. The normal population comes from the healthy population of Nanfang Hospital Health Center of Southern Medical University.

Exclusion Criteria:

1. Preoperative patients have received relevant treatment, such as radiotherapy and chemotherapy;
2. The subject has other diseases, such as tumors in other parts;
3. Patients do not meet the age;
4. There is no guarantee that other eating habits (such as eating fresh fruits and vegetables, not eating preserved foods) and other factors (such as BMI, smoking, drinking, etc.) are basically the same.

Population comes from the Nanfang Hospital of Southern Medical University.