Remarkable Effect of IMATINIB MESYLATE on an Advanced Gastrointestinal Stromal Tumor

Toshitaka Mamiya, Yasuhisa Abe, Shinichi Sasagawa, Hiroshi Sashiyama, Yoshihisa Tateishi and Takenori Ochiai^*

Department of Surgery, Koritu Chosei Hospital, Academic surgery, Chiba University School of Medicine^*

This paper presents a case of an advanced gastrointestinal stromal tumor (GIST) that dramatically responded to IMATINIB MESYLATE. A 82-year-old man had general fatigue with severe anemia. Endoscopic findings showed an ulcer on a large submucosal tumor in the stomach. Abdominal CT scan showed a protruding lesion of approximately 9 cm at the lumen of the gastric body, giant metastatic liver tumors and multiple disseminated tumors in the abdominal cavity. Histological findings of the biopsied specimen showed spindle shaped cells in the submucosa. Immunohistologic staining revealed that the spindle cells were positive for c-kit. Treatment with 300-mg of IMATINIB MESYLATE was started on September 24, 2002. The main tumor and all disseminated tumors had all dramatically reduced after 4 weeks of treatment (reduction rate of 90%). Thus, we evaluated the response as PR. Interstitial pneumonia was observed, but it was immediately improved by steroid-pulse-therapy. As of February 2003, tumors at all sites have continued to respond positively to treatment and the patient remains clinically well.

Key words
GIST, c-kit, IMATINIB MESYLATE

Reprint requests
Yasuhisa Abe Department of Surgery, Koritu Chosei Hospital 2777 Honnou, Mobara-shi, 299-4114 JAPAN

Accepted
April 30, 2003

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