The aim of this trial is to evaluate the safety of laparoscopic resection for GIST whose diameter is ≥2cm and ≤5cm at unfavorable anatomic sites of stomach.

The aim of this trial is to evaluate the safety of laparoscopic resection for GIST whose diameter is ≥2cm and ≤5cm at unfavorable anatomic sites of stomach. Unfavorable anatomic sites are defined by soft tissue sarcoma, NCCN Clinical Practice Guidelines in Oncology (version 2. 2018). The defined laparoscopy unfavorable sites including the anatomic sites of stomach other than greater curvature and front wall, including the less curvature, the posterior wall, and adjacent to cardia and pylorus.

Inclusion Criteria:

• Age from over 18 to under 75 years;
• Gastrointestinal stromal tumor at unfavorable anatomic sites of stomach preoperatively confirmed by endoscopy, ultrasound endoscopy, CT or MRI;
• Diameter of tumor size is ≥2cm and ≤5cm confirmed by contrast CT or MRI;
• Patients whose tumor is resectable by laparoscopic technique at preoperative assessment;
• No evidence of distant metastasis and tumor invading nearby organs at preoperative assessment;
• Performance status of 0 or 1 on ECOG (Eastern Cooperative Oncology Group) scale;
• ASA (American Society of Anesthesiology) score I, II, or III;
• Written informed consent.

Exclusion Criteria:

• Women during pregnancy or breast-feeding;
• Severe mental disorder;
• History of previous upper abdominal surgery (except laparoscopic cholecystectomy);
• History of other malignant disease within the past five years;
• History of previous neoadjuvant imatinib therapy;
• History of unstable angina or myocardial infarction within the past six months;
• History of cerebrovascular accident within the past six months;
• History of continuous systematic administration of corticosteroids within the past month;
• Requirement of simultaneous surgery for other disease;
• Emergency surgery due to complication (bleeding, obstruction or perforation) caused by gastrointestinal stromal tumor;
• FEV1<50% of predicted value;
• Patients with GIST locates at favorable anatomic sites detected by contrast CT, MRI or ultrasound endoscopy at preoperative assessment;
• Patients with GIST diameter<2cm or>5cm detected by contrast CT or MRI;
• Presence of distant metastasis or tumor invading nearby organs at preoperative assessment.

Withdrawal Criteria:

• Patients postoperatively confirmed as non-GIST case by pathology (These cases are enrolled in safe group for future statistic analysis);
• GIST at unfavorable anatomic site diagnosed before operation, while GIST at favorable anatomic site determined by intraoperative exploration;
• Patients confirmed as tumor rupture , metastasis or invading nearby organs intraoperately;
• Patients requiring simultaneous surgical treatment of other diseases;
• Sudden severe complications during the perioperative period (intolerable surgery or anesthesia), which renders it unsuitable or unfeasible to implement the study treatment protocol as scheduled;
• Patients confirmed to require emergency surgery by attending physicians due to changes in the patient's condition after inclusion in this study;
• Patients who voluntarily quit or discontinue treatment for personal reasons at any stage after inclusion in this study;
• Treatment implemented is proven to violate study protocol.

Blinding Method: Open Label