Background: Controversies exist about computed tomography (CT) response evaluation criteria for patients with gastrointestinal stromal tumor (GIST).
Patients and methods: Fifty-one patients with advanced GIST treated second line with sunitinib were evaluated with contrast-enhanced CT every 3 months. Response was rated according to RECIST and Choi criteria. Progression-free survival (PFS) and overall survival (OS) were estimated by Kaplan-Meier analysis.
Results: According to RECIST, patients were categorized as complete response (CR; n = 0; 0%), partial remission (PR; n = 1; 2.0%), stable disease (SD; n = 37; 72.5%), and progressive disease (PD; n = 13; 25.5%) at 3 months. When Choi criteria were applied responses were CR (n = 0; 0%), PR (n = 16; 31.4%), SD (n = 21; 41.1%), and PD (n = 14; 27.5%). Despite these discrepancies, patients rated as SD with RECIST and PR as well as SD according to Choi criteria displayed similar PFS (41.3, 40.7, and 41.3 weeks, respectively) and OS (100.4, 91.6, and 108.0 weeks, respectively). Patients with PD had significantly shorter PFS (10.1 weeks for both criteria) and OS (29.1 weeks for RECIST; 28.9 weeks for Choi) regardless of the response classification applied.
Conclusion: In contrast to absence of progression, discrimination of PR from SD with Choi criteria was of no predictive value.
Trial registration: ClinicalTrials.gov NCT00094029.