• Early esophageal cancer group
  Pathological examination diagnosed as Early esophageal cancer.The ratio of male to female is 3:1, and the age is between 50 and 70 years old.
• Middle and advanced ES group
  Pathological examination diagnosed as Middle and advanced esophageal cancer.
• Normal group
  Confirmed as the normal by health checkups.

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.