This study is aimed:
* to evaluate the dynamic monitoring value of MRD detection for postoperative recurrence in high-risk GIST patients;
* to evaluate the effect of drug holiday mode based on MRD detection on progression-free Survival (PFS) and/or overall survival (OS) after drug withdrawal for high-risk GIST patients who have achieved disease control after long-term use of imatinib; ③ to investigate the response rate of imatinib re-use in patients who developed disease progression after drug withdrawal; ④ to explore whether the "drug holiday" treatment mode based on MRD detection could delay the occurrence of secondary imatinib resistance mutations for high-risk GIST patients with long-term use of imatinib after surgery.
① Age: ≥18 years and ≤75 years;
② The primary lesion (and metastatic lesion) underwent R0 or R1 surgical resection, and patients were clinically diagnosed with high recurrence risk GIST combined with postoperative pathological results;
③ The patient have received imatinib adjuvant therapy for 3 years after surgery, and no gross lesions were detected by imaging examination, and the possibility of drug withdrawal was considered based on the comprehensive judgment of the doctor in charge;
④ The liquid biopsy for baseline ctDNA is negative;
① Fresh or paraffin tissue of the surgical tumor is not available;
② Not receiving the assigned treatment or change therapy before disease progression;
③ Unable to cooperate with follow-up with the study according to defined clinical period;
④ Unable to take or provide defined imaging assessment examinations;