Pretreatment Primary Tumor and Nodal SUVmax Values on ¹⁸F-FDG PET/CT Images Predict Prognosis in Patients with Salivary Gland Carcinoma

Purpose To assess whether primary tumor and nodal ¹⁸F-FDG uptake may predict prognosis in patients with salivary gland carcinoma. Methods We conducted a 2-center, retrospective study on 117 patients with salivary gland carcinoma who underwent ¹⁸F-FDG PET/CT before treatment and were subsequently treated with curative intent between 2004 and 2014. Pretreatment SUVmax of the primary tumor (SUVmax-T) and that of positive nodes (SUVmax-N) were analyzed in relation to clinical outcomes. Results Patients were followed up for a median of 61 months. The following 5-year rates were observed: locoregional control (LRC), 78%; distant metastasis-free survival (DMFS), 67%; progression-free survival (PFS), 62%; and overall survival (OS), 68%. A cutoff value of 7.0 maximized the prognostic impact of both SUVmax-T and SUVmax-N for PFS. Compared with patients with SUVmax-T and SUVmax-N values below the optimal cutoff, those with SUVmax-T and SUVmax-N of 7 or greater showed less favorable 5-year LRC (P < 0.001 and P < 0.001), DMFS (P < 0.001 and P < 0.001), PFS (P < 0.001 and P < 0.001), and OS (P < 0.001 and P < 0.001) rates. Both SUVmax-T of 7 or greater and SUVmax-N of 7 or greater were identified as independent predictors of LRC (P = 0.010 and 0.022), DMFS (P = 0.001 and P = 0.001), PFS (P < 0.001 and P = 0.007), and OS (P = 0.007 and P = 0.002) in multivariable analysis. We therefore devised a prognostic scoring system based on these 2 variables, which was found to be strongly associated with 5-year LRC (P < 0.001), DMFS (P < 0.001), PFS (P < 0.001), and OS (P < 0.001) rates. Conclusions SUVmax of the primary tumor and SUVmax-N on pretreatment ¹⁸F-FDG PET/CT images may be a useful guide in predicting treatment outcomes, especially when combined in a prognostic scoring system.