Objective: To evaluate the efficacy and safety of imatinib mesylate in the treatment of patients as preoperative supplement, or used alone for unresectable and/or metastatic gastrointestinal stromal tumors (GIST).
Methods: A total of 51 cases with advanced GIST were proved pathologically. Among them, CD117 was detected positive in 47 patients and negative in 4 patients; 4 patients received imatinib mesylate before operation and 47 patients with unresectable and (or) metastatic GIST received oral imatinib mesylate daily at dose of 300-800 mg. One patient was lost in follow-up and the objective effect was evaluated in 50 patients.
Results: 3 of the 50 patients (6.0%) achieved complete response (CR), 34 (68%) had partial response (PR), 5 (10.0%) had stable disease (SD) and 8 (20.0%) had progression disease (PD). The median time to progression (mTTP) was 16 months during which most of the patients experienced benefit. 32 patients had been followed up for more then 1 year. The 1-year and 2-year survival rate were 95.3%, 89% respectively. 50 patients were valuable for the toxicity assessment according to the WHO standard. The main toxicity included grade I-II edema of periorbital area and lower limb in 72.0% (36/50) patients, leukopenia was present in 46% (23/50) and intratumoral bleeding in 4.0% (2/50). Other toxicities included mild fatigue (28.0%), abdominal pain (14.0%), efflorescence (18.0%), nausea and vomiting (18.0%).
Conclusions: As an inhibitor of tyrosine kinase, imatinib mesylate is generally well tolerated and has been proved to be effective and safe during prolonged treatment of patients with advanced gastrointestinal stromal tumors. Its toxicity is acceptable.