Total metabolic tumor volume by 18F-FDG PET/CT for the prediction of outcome in patients with non-small cell lung cancer.

Abstract

Metabolic tumor volume (MTV) and total lesion glycolysis (TLG) are imaging parameters derived from 18F-FDG PET/CT that have been proposed for risk stratification of cancer patients. The aim of our study was to test whether these whole-body volumetric imaging parameters may predict outcome in patients with non-small cell lung cancer (NSCLC). Sixty-five patients (45 men, 20 women; mean age ± SD, 65 ± 12years), with histologically proven NSCLC who had undergone 18F-FDG PET/CT scan before any therapy, were included in the study. Imaging parameters including SUVmax, SUVmean, total MTV (MTVTOT) and whole-body TLG (TLGWB) were determined. Univariate and multivariate analyses of clinical and imaging variables were performed using Cox proportional hazards regression. Survival analysis was performed using Kaplan-Meier method and log-rank tests. A total of 298 lesions were analyzed including 65 primary tumors, 114 metastatic lymph nodes and 119 distant metastases. MTVTOT and TLGWB could be determined in 276 lesions. Mean value of MTVTOT was 81.83ml ± 14.63ml (SE) whereas mean value of TLGWB was 459.88g ± 77.02g (SE). Univariate analysis showed that, among the variables tested, primary tumor diameter (p = 0.0470), MTV of primary tumor (p = 0.0299), stage (p < 0.0001), treatment (p < 0.0001), MTVTOT (p = 0.0003) and TLGWB (p = 0.0002) predicted progression-free survival in NSCLC patients, while age (p = 0.0550), MTV of primary tumor (p = 0.0375), stage (p < 0.0001), treatment (p < 0.0001), MTVTOT (p = 0.0001) and TLGWB (p = 0.0008) predicted overall survival. At multivariate analysis age, TLGWB and stage were retained in the model for prediction of progression-free survival (p < 0.0001), while age, MTVTOT and stage were retained in the model for prediction of overall survival (p < 0.0001). Survival analysis showed that patients with TLGWB ≤ 54.7g had a significantly prolonged progression-free survival as compared to patients with TLGWB > 54.7g (p < 0.0001). Moreover, overall survival was significantly better in patients showing a MTVTOT ≤ 9.5ml as compared to those having MTVTOT > 9.5ml (p < 0.0001). Similar results were obtained in a subgroup of 43 patients with advanced disease (stages III and IV). Whole-body PET-based volumetric imaging parameters are able to predict outcome in NSCLC patients.