A Study of the Postoperative Course in Cases of GIST of the Stomach. The Efficacy of Imatinib in Cases of Recurrence

Background: The postoperative course of cases of gastrointestinal stromal tumor (GIST) of the stomach was studied in patients who underwent surgery in this Department. In addition, treatment with the molecular-targeted drug imatinib was studied in cases of recurrence. Patients and Methods: We studied 40 cases with a diagnosis of GIST of the stomach where the patient subsequently underwent surgery in this Department between July 1985 (when this facility opened) and December 2007. Six of these cases involved patients with carcinoma or carcinoid tumors, which could have affected the procedure and prognosis, and 2 cases involved patients who developed cancer during the postoperative course of the GIST. Therefore these 8 patients were excluded, thus resulting in the study of a total of 32 patients. Results: The male:female ratio for the 32 patients was 17:15, the average tumor size was 4.7±3.4 cm (with a range of 1.3-16.0 cm), and the median follow-up was 92.2±73.7 months (with a range of 2-238 months). Recurrence occurred in 6 out of the 32 patients (18.8%) and was observed in the liver of 5 patients, in the lungs of 2 patients, in the peritoneum of 2 patients, locally in 1 patient, and in the bone of 1 patient (including patients with multiple sites). With respect to the tumor size, the incidence of recurrence of tumors smaller than 2 cm was 0%, 16.7% for patients with tumors 2 to 5 cm in size, and 27.3% for thesewith tumors larger than 5 cm. The incidence of recurrence was particularly marked in patients with tumors larger than 10 cm (66.7%). The treatment for recurrence was transcatheter arterial embolization for 1 patient and imatinib for 5 patients. In cases where imatinib was administered, 1 patient exhibited partial response, 1 patient exhibited stable disease, and 3 patients exhibited progressive disease, indicating a response rate of 20%. Postoperative recurrence of GIST of the stomach in this study occurred in 6 of 32 patients (18.8%). The incidence of recurrence of tumors larger than 10 cm was 2 out of 3 patients. Conclusion: In cases of recurrence, the response rate to imatinib was 20%. Imatinib was effective against GIST that were positive for KIT protein, but future study is needed to clarify the risk factors for recurrence and indications for adjuvant therapy in cases of GIST.