Prognostic relevance of early response to induction chemotherapy (IC) in locally advanced NSCLC by 18FDG positron emission tomography (PET)

Abstract

7001 Background: In locally advanced NSCLC the performance of response monitoring after combined modality treatment (CMT) using standard CT criteria is limited. Identifying patients with a response to IC in a more reliable way at an early stage of treatment could have major clinical implications. 18FDG PET may be used to assess the effect of IC. The objective of this study was to determine the accuracy of early response measurements using 18FDG PET with respect to survival of stage IIIA-N2 NSCLC patients undergoing CMT. Methods: Consecutive stage IIIA-N2 NSCLC patients who received 3 cycles of platinum based IC were included. A dynamic PET scan was performed prior to the start of IC and after course 1 and 3. CT scan of thorax and upper abdomen was performed before and at the end of IC. PET analysis of the primary tumor was performed by Patlak graphical analysis at 10–60 minutes post injection. The mediastinal lymphnode (MLN) status was assessed visually, and analysed using Kaplan Meier plots and the logrank test (p < 0.05). Cox proportional hazard regression analysis was used to assess the prognostic value of the baseline and %change in 18FDG PET-uptake (MRglu) with respect to survival time. Results: 47 patients (33 men, 14 women, mean age 63 (range 30–81) years) were included. Median follow up is 28 months. MLN status by PET after 1 cycle of IC did not show a significant relation with survival (p=0.74). Baseline Mrglu-value together with the percentage decrease in uptake after one course was related to survival (p=0.05 and p=0.02 respectively in the combined model). The percentage decrease after 3 courses was even more predictive for survival. Conclusions: Response assessment to CMT in stage IIIA-N2 NSCLC using the %change in uptake of 18FDG with PET after 1 and 3 courses of IC is correlated with survival. No significant financial relationships to disclose.