Endoscopic Full Thickness Resection of Gastric Subepithelial Tumors (FROST)

Inclusion Criteria: * presence of a subepithelial gastric tumor with signs of potential malignancy in endoscopic ultrasound * age 18 years or older * participant has given informed consent Exclusion Criteria: * tumor size \> 40 mm (endosonographic measurement) or large extramural tumor mass * signs of systemic dissemination of tumor * current presence of a different neoplastic disease (except after successful curative treatment without continued medication) * former surgery or disease of esophagus or stomach that impedes insertion of the suturing device * moribund patient * limited possibility to give informed consent (e.g. language barrier, psychiatric disease) * pregnancy and lactation period