Prognostic Significance of Pretreatment Primary Tumor and Nodal SUVmax on 18F-FDGPET/CT Imaging in Patients with Salivary Gland Carcinoma

Abstract

To investigate the prognostic significance of primary tumor and nodal Fluorine-18-fluorodeoxyglucose (18F-FDG) uptake in patients of salivary gland carcinoma (SGC) who have undergone curative treatment. This multicenter study retrospectively enrolled 117 SGC patients who had pretreatment 18F-FDG PET/CT and were treated with curative intent between 2004 and 2014. The most common histological subtypes were adenoid cystic carcinoma (N= 39, 34%), mucoepidermoid carcinoma (N = 28, 24%), and adenocarcinoma (N = 17,15%). Treatment outcomes were examined in relation to maximum standardized uptake values of the primary tumors (SUVmax-T) and positive-nodes (SUVmax-N) on pretreatment 18F-FDG PET/CT. After a median follow-up of 61 months, the 5-year locoregional control (LRC), regional control (RC), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) rates were 78%, 87%, 67%, 62%, and 68%, respectively. The median SUVmax-T and SUVmax-N were 7.2 (range, 2.0−27.6) and 7.6 (range, 2.0−25.8), respectively. The optimal cutoff values of SUVmax-T and SUVmax-N which maximized the prognostic significance for PFS were both 7.0. Significantly lower 5-year LRC (P <0.001 and <0.001), DMFS (P <0.001 and <0.001), PFS (P <0.001 and <0.001) and OS (P <0.001 and <0.001) rates were observed in patients with SUVmax-T ≥7 and SUVmax-N ≥7, respectively. Multivariate analyses demonstrated that both SUVmax-T ≥7 and SUVmax-N ≥7 were significant independent predictors of LRC (P = 0.010 and 0.022), DMFS (P = 0.001 and 0.001), PFS (P <0.001 and = 0.007) and OS (P = 0.007 and 0.002), and SUVmax-N ≥7 significantly correlated with inferior RC (P <0.001). Subgroup analyses indicated that SUVmax-T predicted 5-year PFS in patients with adenoid cystic carcinoma (P = 0.006), mucoepidermoid carcinoma (P = 0.019), and adenocarcinoma (P = 0.041). Both pretreatment SUVmax-T and SUVmax-N on 18F-FDG PET/CT predicts treatment outcomes and survival in SGC patients treated with curative intent.