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

Abstract

Objective: 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).

Methods: Sixty-five patients (45 men, 20 women; mean age ± SD, 65 ± 12 years), with histologically proven NSCLC who had undergone 18F-FDG PET/CT scan before any therapy, were included in the study. Imaging parameters including SUV_max, SUV_mean, total MTV (MTV_TOT) and whole-body TLG (TLG_WB) 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.

Results: A total of 298 lesions were analyzed including 65 primary tumors, 114 metastatic lymph nodes and 119 distant metastases. MTV_TOT and TLG_WB could be determined in 276 lesions. Mean value of MTV_TOT was 81.83 ml ± 14.63 ml (SE) whereas mean value of TLG_WB was 459.88 g ± 77.02 g (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), MTV_TOT (p = 0.0003) and TLG_WB (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), MTV_TOT (p = 0.0001) and TLG_WB (p = 0.0008) predicted overall survival. At multivariate analysis age, TLG_WB and stage were retained in the model for prediction of progression-free survival (p < 0.0001), while age, MTV_TOT and stage were retained in the model for prediction of overall survival (p < 0.0001). Survival analysis showed that patients with TLG_WB ≤ 54.7 g had a significantly prolonged progression-free survival as compared to patients with TLG_WB > 54.7 g (p < 0.0001). Moreover, overall survival was significantly better in patients showing a MTV_TOT ≤ 9.5 ml as compared to those having MTV_TOT > 9.5 ml (p < 0.0001). Similar results were obtained in a subgroup of 43 patients with advanced disease (stages III and IV).

Conclusions: Whole-body PET-based volumetric imaging parameters are able to predict outcome in NSCLC patients.

Keywords: 18F-FDG PET/CT; Metabolic tumor volume; Non-small cell lung cancer; Prognosis; Total lesion glycolysis.