Use of early 18f-fluorodeoxyglucose-positron emission tomography to predict clinical outcome of patients with advanced non-small cell lung cancer on gefitinib treatment versus carboplatin plus paclitaxel.

Abstract

10577 Background: Early prediction of clinical efficacy is of great value in cancer patients in avoiding unnecessary toxicities and giving them another chance for different treatments. This study aimed to assess the 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) at 3 days on treatment as an early predictor of clinical outcome in patients with advanced non-small cell lung cancer (NSCLC) treated with gefitinib and in those treated with cytotoxic chemotherapy. Methods: This study comprised two groups: patients with stage IIIB or IV NSCLC were treated with gefitinib (250mg) once daily (gefitinib group) or with carboplatin (AUC 6, day 1) plus paclitaxel (200mg/m2, day 1) q21 days (CP group) according to the physicians’ choice. FDG-PET was performed before, 3 days on and 28 days on each treatment. Reduction of tumor FDG uptake was assessed by using standardized uptake value (SUV). Metabolic response was defined as reduction of FDG uptake in the tumor ≥ 25% according to the criteria of the European Organization for Research and Treatment of Cancer. Metabolic response was correlated with clinical outcomes. Results: This study included 38 patients: 19 in gefitinib group and 19 in CP group. Reduction of SUV at 3days on treatment preceded tumor shrinkage more closely in gefitinib group. Metabolic response was significantly correlated with longer progression-free survival (PFS) in gefitinib cohort (median PFS 15.8 months [95% CI 13.2-18.4] vs. 3.7 months [95% CI 0.1-8.0], p < 0.001), but not in CP group (median PFS 5.7 months vs. 2.9 months, p = 0.054). Furthermore, metabolic response was significantly correlated with longer overall survival (OS) in gefitinib group (median OS 28.7 months [95%CI 23.5-33.9] vs. 9.8 months [95% CI 2.1-17.5], p = 0.009), but not in CP group (median OS 13.9 months vs. 10.5 months, p = 0.56). In multivariate analysis using Cox hazards models, metabolic response was a significant predictive factor of PFS and OS. Conclusions: Reduction of SUV levels on FDG-PET at 3 days on treatment may predict response and survival in gefitinib-treated patients with advanced NSCLC.