Abstract
1090
Background: Semi-quantitative analysis of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) in head and neck cancers (HNC) is still undergoing investigation and development.
Purpose: To evaluate the prognostic value of metabolic and volumetric information derived from 18F-FDG-PET/CT prior to treatment in patients with HNC.
Methods: Pre-treatment 18F-FDG-PET/CT scans of fifty-four HNC patients with squamous cell carcinoma (47 males, 7 females, median aged 59.5 years, range: 37.2-78.6) were collected retrospectively. All of the patients underwent linear accelerator (LINAC) for radiation therapy in their course of treatment. An observer blinded to the patients’ outcome performed the measurements. On PET, active malignant lesions in the head and neck area were segmented with an adaptive thresholding system (ROVER software, ABX GmbH, Radeberg, Germany). Conventional measures of PET quantification, namely SUVmean and SUVmax, and volumetric parameters, namely total lesion glycolysis (TLG) and metabolic tumor volume (MTV), were obtained. Receiver operating characteristic (ROC) was used to determine the area under the curve (AUC). Univariate Cox regression analysis was performed to identify the factors associated with progression-free survival (PFS). PFS was measured from the date of start of treatment until disease progression or death.
Results: Median follow up of the patients was 37.4 months (range: 2.5-137.4). AUCs for SUVmean, SUVmax, TLG and MTV were .425 (95% CI: .266-.585), .464 (.305-.623), .592 (.432-.752) and .679 (.572-.831), respectively [Figure 1]. In a univariate Cox regression analysis, TLG (HR: 1.002, 95% CI: 1-1.005; p= .04) and MTV (HR: 1.039, 95 % CI: 1.018-1.06; p< .001) were prognostic factors for PFS. SUVmean and SUVmax failed to show a significant correlation with PFS (p> .05).
Conclusions: We observed that volumetric methods of 18F-FDG-PET/CT quantification were superior to conventional metrics for predicting PFS. This is in accordance with the results of previous studies showing that volumetric PET metrics are more reliable for prediction of survival in malignancies, including head and neck cancers.