Surgery and imatinib therapy for liver oligometastasis of GIST: a study of Japanese Study Group on GIST.

We conducted a multicenter prospective study to clarify the efficacy and safety of surgery and imatinib for liver oligometastasis of gastrointestinal stromal tumors. Eligible gastrointestinal stromal tumor patients were enrolled in the surgery trial or the imatinib trial. Primary endpoints were recurrence-free survival and progression-free survival, respectively. The trials were prematurely terminated due to amendment of guidelines for adjuvant imatinib therapy and low patient accrual. In the surgery trial, all the six patients showed hepatic recurrence: median recurrence-free survival was 145 days (range: 62-1366 days). Of the five patients receiving salvage imatinib therapy, two showed progressive disease although no death was observed. Of the five patients enrolled in the imatinib trial, one died of pneumonia after progressive disease, and four had not shown progressive disease as of last visit. The results suggest that liver oligometastasis of gastrointestinal stromal tumor may not be controllable by surgery alone and require concomitant imatinib therapy.