This study will evaluate the efficacy and safety of C2 CryoBalloonTM Ablation System for the cryoablation of dysplastic squamous tissue in patients with moderate to severe esophageal squamous epithelium dysplasia.

Inclusion Criteria:

1. Male or female of 18 to 80 years old (including 18 and 80 years old).
2. At least one unstained lesion (USL) in the esophagus upon high resolution upper gastrointestinal endoscopy with Lugol's staining. Flat (Paris type 0-IIb) USL, with the total area of one or more USLs having a maximum longitudinal size of 6 cm and covering a maximum of one-half of the esophageal circumference.
3. Patients with one or more biopsy confirmed esophageal squamous epithelium dysplasia areas within 6 months prior to enrollment, and the pathological diagnosis is moderate to severe esophageal squamous epithelium dysplasia.
4. No potential of lymph node metastasis by preoperative comprehensive evaluation.

Exclusion Criteria:

Inclusion criteria:

1. Male or female of 18 to 80 years old (including 18 and 80 years old).
2. At least one unstained lesion (USL) in the esophagus upon high resolution upper gastrointestinal endoscopy with Lugol's staining. Flat (Paris type 0-IIb) USL, with the total area of one or more USLs having a maximum longitudinal size of 6 cm and covering a maximum of one-half of the esophageal circumference.
3. Patients with one or more biopsy confirmed esophageal squamous epithelium dysplasia areas within 6 months prior to enrollment, and the pathological diagnosis is moderate to severe esophageal squamous epithelium dysplasia.
4. No potential of lymph node metastasis by preoperative comprehensive evaluation.
5. The patients are self volunteered to participate in the trial and will sign an informed consent form prior to enroll.

Exclusion criteria:

1. Females who are pregnant, lactating or plan to get pregnant during the study.
2. Known hypersensitivity to iodine.
3. Lesions within the target area such as: obvious ulcer; varices at risk of bleeding; active inflammation due to esophageal reflux into the treatment area; lesions view being not flat, or containing unfavourable unstained lesions (USLs) outside the designated treatment areas.
4. Esophageal stenosis preventing the passage of the endoscope to the treatment area. Esophageal stenosis or stricture preventing advancement of a therapeutic endoscope within 4 cm of the treatment area.
5. Having previously received Heller surgery: any previous ablative esophageal surgery (photodynamic therapy, multipolar electrical coagulation, argon plasma coagulation, laser treatment) or any previous esophageal surgery except for anti-reflux surgery.
6. Suffering from any cancer in the past 5 years.
7. Severe bleeding potential; patients on anti-coagulative therapy or stopping using anti-coagulative drugs for less than 7 days before enrollment or with impaired coagulation.

9) Patients with unstable vital signs 10) Anti-human immunodeficiency virus (HIV) antibody positive, both syphilis serology Treponema pallidum-specific antibody test and rapid plasma reagin positive.

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