The goal of this observational study is to accurate diagnose the stage of esophageal squamous cell carcinoma in order to help physicians to decide the appropriate clinical treatment. The main question it aims to answer is:

• To get early accurate diagnosis of the invasion depth of esophageal squamous cell carcinoma by narrow-band imaging endoscopy data.

Participants' clinical informations from routine examinations and treatments will be collected, there will be no harm to participants.

Inclusion Criteria:

1. Age ≥ 18 years old, regardless of gender;
2. Performing esophageal ESD surgery due to esophageal mucosal lesions;
3. Pathological evaluation of ESD specimens.

Exclusion Criteria:

Pathological examination after ESD surgery ruled out esophageal squamous cell carcinoma.

Around 500 cases.