To Explore the Optimal Therapeutic Window for Imatinib in the Adjuvant Treatment of Intermediate and High-risk Gastrointestinal Stromal Tumors

Inclusion Criteria: 1. Patients using imatinib as adjuvant therapy for GIST from 2015\~2025 2. ECOG (Eastern Cooperative Oncology Group performance status) physical fitness score ranges from 0 to 4 3. Local GIST diagnosis confirmed by histology 4. The surgical resection type of primary GIST (R0 / R1) was documented 5. Regular long-term maintenance doses of imatinib at steady-state trough concentrations ≥ 3 times Exclusion Criteria: 1. Known GISTs insensitive to imatinib, such as PDGFRA exon 18 D842V mutation, KIT exon 17 mutation, SDH-deletion type, NF-1 mutation, and NTRK fusion mutation 2. Those with poor medication adherence 3. Missing important diagnostic and treatment data