Effect of Imatinib Mesylate in Recurrent Gastric GIST

Lee, Jung Sun; Oh, Sung Tae; Kim, Young Jin; Choi, Won Yong; Yook, Jung Hwan; Kim, Byung Sik; Kim, Joeng Sun; Kim, Tae Won

Abstract

PURPOSE
Gastrointestinal stromal tumor (GIST) is the designation for c-kit signal driven mesenchymal tumor. A great majority of these tumors occur in the stomach and small intestine, and rarely in the colon, rectum and esophagus. Metastatic or recurrent GIST must be resected surgically because it is resistant to conventional cytotoxic chemotherapy. Following recent evidence for the dramatic effect of Imatinib mesylate (Glivec), Glivec has become available in our country since June 2001 without insurance coverage. Although some doubt remained, we applied Glivec to recurrent GIST patients with great expectation. METHODS: A retrospective analysis was made for 16 GIST patients who were resected during 2001. Follow up duration was 19 to 29 months. All pathologic slides were reexamined immunohistochemically by an experienced pathologist. Clinicopathologic comparison between the recurred and non-recurred groups was summarized into the tables. The therapeutic and side effects of Glivec were surveyed. CT scan files were reviewed to decided tumor regression or progression. RESULTS: Fifteen GISTs were resected in 2001. Seven cases recurred during 19 to 29 months of follow up. The recurred group was characterized by huge tumor size (mean 14 cm), serosal invasion and more than 10 mitosis in 50 HPF. A daily dose of 400 mg of Glivec was prescribed to every recurred GIST patients and CT scan was followed serially. The therapeutic effect of Glivec effect was drastic but variable; complete tumor remission (n=3), rebounded tumor growth at the same location after remission (n=1), and recurrence at another location after complete remission (n=2). CONCLUSION: Glivec drastically reduced the size of recurrent gastric GIST initially. However, it is not clear how long Glivec should be taken at a great expense in fear of rebounded growth after abstaining. It appears that reoperation is necessary without delay when tumor remission slows down.