Total lesion glycolysis (TLG) at baseline FDG-PET/CT compared with maximum standard uptake value (SUVmax) to predict survival in non-small cell lung cancer (NSCLC)

7579 Background: SUVmaxat baseline FDG-PET has been reported as a significant prognostic factor while recent studies suggest that metabolic tumor volume (MTV) may be more important factor in patients with NSCLC. We hypothesized that TLG is a better prognostic factor than either SUVmax or MTV alone for overall survival (OS) and progression free survival (PFS) in NSCLC because it integrates both volumetric and biologic activity. Methods: The study population included a prospectively recruited cohort of stage I-III NSCLC patients treated with chemoradiation. FDG PET/CT scans were performed within 2 weeks from treatment start. The SUV in the tumor was normalized to that of the background level in the middle of ascending aorta to minimize the confounding effect from inter-scan variation in SUV measurement. MTV was delineated by auto-threshold at 1.5 times background level in the aorta followed by knowledge based manual editing. Mean and maximum SUV normalized to the background level were computed. TLG was calculated as the product of lesion SUVmean and MTV. Results: A total of 96 patients with minimum follow-up of 1 year were eligible. The median follow-up among survivors was 30 months. Univariate analysis demonstrated that MTV and TLG were significant factors for both OS and PFS (all Pmean and PFS (P=0.013), but there was no significant association between SUVmean and OS. SUVmax was not a significant factor for either OS or PFS (all P>0.05). Under multivariate Cox regression analysis, MTV (HR= 2.62, P= 0.003) and NSUVmean (HR=0.351, P=0.003) were significantly associated with PFS; but only TLG was significantly associated with OS (HR=2.14, P=0.006)adjusted by of TNM stage and other clinical factors. Conclusions: These results support our hypothesis that metabolic tumor volume and biologic average glucose metabolic activity of this volume are more important prognostic factors for overall prognosis than SUVmax in NSCLC patients treated with chemoradiation. Should this be validated by independent studies, future clinical trial should take this into consideration for individualized care.