The goal of this clinical trial is to learn if tranilast works to prevent esophageal stricture after circumferential endoscopic submucosal dissection (cESD) in adults. It will also help us learn more about the safety of tranilast. The main questions it aims to answer are: 1. Does tranilast reduce the occurence of esophageal stricture in participants after cESD? 2. What medical problems do participants have when taking tranilast.

Researchers will compare tranilast to prednisone (a steroid used in clinical practice with potential defects) to see if tranilast works well to prevent esophageal stricture.

Participants will: 1. Take tranilast or prednisone every day for 8 weeks. 2. Attend visit (at clinic or phone) once every 2 weeks for checkups and tests until 16 weeks. 3. Keep a diary of their symptoms and let researchers know during the 16 weeks follow up.

Esophageal strictures are a frequent complication after cESD for superficial esophageal tumors, which significantly affects patients' quality of life and often necessitates repeated endoscopic interventions. Currently, steroids are widely used to prevent post-cESD strictures, but their side effects, including increased risks of infection and delayed wound healing, limit their use. Tranilast, an anti-inflammatory and antifibrotic agent, has shown potential in preventing fibrosis in preclinical studies, but its clinical efficacy in preventing esophageal stricture after cESD remains unclear.

This randomized, parallel, single-blinded non-inferiority trial aims to compare the efficacy and safety of tranilast with steroids in preventing esophageal strictures post-cESD. The primary outcome is the incidence of esophageal stricture within 16 weeks after cESD. It is a composite outcome defined as the inability to pass a standard endoscope (diameter 10.8 mm) through the stricture site at 16 weeks, or the presence of clinical symptoms of esophageal stricture (such as difficulty swallowing solid food) occurring before the endoscopic assessment at 16 weeks. Secondary outcomes include drug-related side effects, postoperative adverse events, and quality of life scores. This study will provide valuable insights into whether tranilast can serve as an effective and safer alternative to corticosteroids in this setting.

Inclusion Criteria:

1. age>18 and proficient in Mandarin.
2. underwent cESD treatment for superficial esophageal neoplasms.
3. agree to sign an informed consent form.

Exclusion Criteria:

1. allergic to tranilast.
2. with severe comorbid conditions.
3. pregnant or breastfeeding.

The decision regarding the sharing of individual participant data is currently pending further assessment of data protection laws and privacy concerns. We are also awaiting approval from the ethics committee before making a final decision.

Single-Blind Method with Investigator Blinding

Specific blinding measures:

1. Randomization and drug allocation: Randomization and drug allocation should be managed by a third party (e.g., data management team or pharmacist). The treatment options (Tranilast or steroids) should be distributed in identical appearance, packaging, and dosage forms to ensure that the investigators cannot determine the group assignment based on the drug's appearance.
2. Protection of subject information: Ensure that investigators have no access to any information regarding the drug name and group assignment. Anonymous numbers or subject codes can be used for labeling, with only the personnel or system responsible for drug allocation knowing the specific group assignments.
3. Data monitors or independent assessors: Independent monitors or assessors can be introduced, responsible only for follow-up and evaluation of post-procedure stricture, without knowledge of the patients' treatment groups.