Pretreatment quantitative ¹⁸ F-FDG PET/CT parameters as a predictor of survival in adenoid cystic carcinoma of the salivary glands

Purpose: The aim of this study was to determine the unique prognostic value of quantitative ¹⁸ F-FDG PET/CT parameters to assess progression-free survival (PFS), distant metastasis-free survival (DMFS), and overall survival (OS) in patients with salivary gland adenoid cystic carcinoma (ACC). Methods: We performed a retrospective study including 23 patients (15 men, 8 women; median age, 58 years; range, 21–91 years) with salivary gland ACC between January 2009 and October 2017 who underwent ¹⁸ F-FDG PET/CT scan prior to treatment. Maximum, mean, peak, tumor-to-mediastinal blood pool and tumor-to-liver standardized uptake values (SUV _max , SUV _mean , SUV _peak , SUV _ratio[med] and SUV _ratio[liver] ), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were obtained from ¹⁸ F-FDG PET/CT. The prognostic value of quantitative ¹⁸ F-FDG PET/CT parameters and other clinicopathological variables were evaluated utilizing the Cox proportional regression analysis. Results: The 3-year and 5-year OS for all the patients were 90.9%, and 62.3%, respectively. Log rank test determined that the SUV _ratio[med] , SUV _ratio[liver] , MTV and TLG were predictive factors of DMFS, PFS, and OS (p < 0.05), furthermore, SUV _max , minor salivary gland tumors and DM at initial diagnosis (M1 stage) were predictor for PFS; M1 stage and overall stage 3–4 predicted DMFS (all p < 0.05). Cox regression analyses confirmed that the higher SUV _ratio[med] , SUV _ratio[liver] , MTV, and TLG values predicted DMFS, PFS and OS independently, whereas SUV _max was an independent predictor of only PFS (p < 0.05). Conclusions: The pretreatment metabolic ¹⁸ F-FDG PET/CT parameters may reflect tumor aggressiveness in patients with salivary gland ACC and may potentially be utilized as a prognostic biomarker.