Surgical treatment of patients (pts) with gastrointestinal stromal tumors (GIST) after imatinib mesylate (IM) therapy

Abstract

9037 Background: Complete response (CR) during IM therapy due to unresectable/metastatic GIST is restricted to a few pts and progression rate is about 10%/year. The aim of the study was to analyze the surgical possibilities of unresectable/metastatic GIST CD117(+) pts during IM treatment. Methods: We analyzed the results of surgery in 118 consecutive pts (69 male - M, 49 female - F, median age 55) treated with IM for inoperable/metastatic GIST CD117(+) between 09/2001 and 09/2004 in 1 center. Median follow-up time was 7 months [m] (range: 1 - 18 m). Results: Surgery was used as adjuvant treatment in 16 pts (group I - 14%, 9M, 7F, median age 56) for R0/R1 resection of residual disease after CR/partial response (PR - according to RECIST) no longer responding to IM treatment (median duration of IM treatment 14 m, range: 4–30 m) and as salvage therapy in 7 pts (group II: 5M, 2F, median age 52), who progressed on initially successful IM (median duration of IM treatment 20 m, range: 10–31m). In group I the viable GIST cells were not detected histologically in resection specimens in only 3 pts. Surgical procedures in group I consisted of 5 extensive liver resections (in 2 cases combined with radiofrequency ablation), 7 resections of intraperitoneal lesions with omentectomy, 1 partial gastrectomy and 3 explorative laparotomies only (in CR). Initially 5 pts in group I did not received further IM and we observed 3/5 recurrences (IM reintroduction demonstrated again PR). In other 11 pts, who continue IM after surgery, we do not observe disease relapse. Complications comprised 3 prolonged ileus treated conservatively. In group II after resection of progressive lesions (resistant to IM) we continued IM therapy, but in 4/7 pts we observed subsequent progression. In this group surgery was associated with a high risk of complications: 1 perioperative death due to uncontrolled bleeding and 1 ileus treated surgically. Conclusions: Surgical removal of residual disease during IM treatment may allow for CR in selected GIST pts after PR, theoretically prolonging durable remission, but it is necessary to continue IM after R0/R1 surgery for maintaining CR. In case of progression during IM the indications for surgery should be individualized. No significant financial relationships to disclose.