This is a randomized, single-center clinical trial that will compare the efficacy of two substances used in the submucosal cushion formation stage of endoscopic submucosal resections of early esophageal malignant neoplasms. Such substances are hyaluronic acid in the form of TS-905 Blue Eyeₒ and hydroxyethylamide (Voluven®).

1. Design of the study:

   This is a randomized clinical trial in a single center. The lesions will be randomized into three blocks based on the diameter of the largest axis (less than 3 cm, between 3 - 5 cm and greater than 5 cm).

2. Selection of patients:

   The population studied will be patients with early esophageal neoplasia diagnosed and/or referred for submucosal endoscopic dissection at the São Paulo Cancer Institute (ICESP), University of São Paulo.

3. Evaluation of effectiveness and definitions:

Effectiveness will be measured from the degree of usefulness. The degree of utility will be determined from two variables: obtaining or not a complete block resection and additional number of submucosal injections performed during endoscopic dissection. The solution that results in a complete block resection with a number of additional injections of 0 (excellent utility degree) or 1 (good utility degree) will be considered effective.

Inclusion Criteria:

• Patients over 18 years of age
• Superficial esophageal adenocarcinoma or squamous cell carcinoma with indication of ESD after discussion in a multidisciplinary oncological board
• Signed informed consent form

Exclusion Criteria:

• Residual or recurrent esophageal lesions
• Ulcerated esophageal lesions
• Patients with severe cardiovascular, kidney or liver disease
• History of hypersensitivity to hyaluronic acid
• Pregnant or lactating women