Endoscopic submucosal dissection (ESD) is a relatively new modality for the treatment of superficial gastrointestinal neoplasia and especially in the diagnosis and treatment of submucosal tumors. ESD has become a minimal invasive alternative to surgery but requires a high degree of endoscopic skills to be performed safely, it is time consuming, and less safe than endoscopic mucosa resection.

New endoscopic instruments have been developed to increase the efficacy and safety of ESD, and a combined endoscopic instrument (HybridKnife) has been developed and evaluated with promising results in animal studies. This HybridKnife allows high-pressure water-jet (submucosal) dissection, as well as cutting and coagulation and makes ESD possible without changing instrument.

The purpose of this study is to evaluate the feasibility and safety of using HybridKnife for ESD in humans.

Inclusion Criteria:

• Submucosal tumor (< 4 cm)
• Mucosal tumor (T1) in patients unsuitable for surgery

Exclusion Criteria:

• Endoscopic ultrasound (EUS) or CT signs of metastasis
• Insufficient access to tumor

Patients referred to the Endoscopic Section at the Department of Surgery, Odense University Hospital, with a mucosal or submucosal tumor in the esophagus or stomach.