Purpose: The objective of this study was to examine the predictive role of pretreatment total lesion glycolysis (TLG) of the whole-body and primary tumors in patients with pharyngeal cancer (PC) treated with definitive radiotherapy.
Methods: The retrospective analysis examined 74 PC patients treated with radiotherapy. All patients received pretreatment with F-FDG PET/CT. Several autosegmentation methods were used to determine the PET/CT-based metabolic tumor volume (MTV), TLG of the primary tumor, and whole-body TLG (TLGw) for each patient. Overall survival (OS), disease-free survival (DFS), and primary relapse-free survival (PRFS) were examined according to the cutoffs of the median values for MTV, TLG, and gross tumor volume of the primary tumor. Independent prognosticators were identified using Cox regression analysis.
Results: After a median follow-up of 33 months, 42 patients remained disease-free, and 32 patients experienced cancer recurrence. Multivariate analysis of the OS and DFS showed that the application of 40% of the maximal uptake of whole body TLG(TLGw40%) was the only predictor of OS or DFS. Patients who had tumors with TLGw40% greater than 92 g had significantly lower 3-year OS and DFS compared with patients who had smaller TLGw. The independent predictors for PRFS were MTV greater than the SUVmax of 2.5 (MTV2.5).
Conclusions: For PC patients treated with definitive radiotherapy, pretreatment with TLGw40% achieved the optimal predictive value for OS and DFS, and MTV2.5 was a prognosticator for PRFS.