Early prediction of clinical response to first-line treatment with gefitinib using integrated FDG-PET for patients with advanced non-small cell lung cancer.

Abstract

e18049 Background: Early prediction of clinical response is of great value in patients with advanced non-small cell lung cancer (NSCLC) in avoiding unnecessary toxicity and giving them another chance for different treatment. This study aimed to assess the integrated 18-fluorodeoxyglucose positron emission tomography (FDG-PET) at 3 days after treatment as a tool for early response predictor in the patients treated with gefitinib or carboplatin plus paclitaxel (CP). Methods: Patients with stage IIIB or IV NSCLC were scheduled to receive first-line treatment were eligible for this study. Patients were treated with gefitinib (250mg) once daily or with CP every 3-week cycle as first-line treatment. FDG-PET was performed before and 3 day after initiation of each treatment. Based on previous studies, a reduction of tumor FDG uptake was assessed by using standardized uptake value (SUV). ROC analyses were performed to compare the results of the visually interpreted FDG-PET findings and the findings obtained with the use of an SUV threshold. Results: A total 38 patients were included in this study. Nineteen patients (50%) received gefitinib, and 19 (50%) received CP. The overall response rate (RR) was 36% with 7 partial response (PR) in gefitinig group and 16% with 3 PR in CP group. The optimal differentiation achieved by a cut-off value in reduction of SUV level was 20% in gefitinib group and 15% in CPgroup. Applying this cut-off value as a criterion for a metabolic response, sensitivity and specificity for predicted clinical response was of 91% and 100% in patients with gefitinib, 81% and 67% in patients with CP, respectively. , Metabolic responder had significant longer survival than non-responder in gefitinib group (median overall survival (OS): 22.6m, 95%CI: 7.4-37.8 vs median OS: 7.7m, 95%CI: 1.7-13.7, p=0.04), while there was no correlation between a reduction of SUV level and OS in CP group (median OS: 13.9m, 95%CI: 10.0-17.8 vs median OS: 10.5m, 95%CI: 7.3-13.7, p=0.56). Conclusions: The reduction of SUV level by using FDG-PET at 3 day after treatment can predict response and survival in gefitinib-treated patients.