Diagnostic and Prognostic Utility of ¹⁸F-FDG PET/CT in Recurrent Salivary Gland Cancers.

Abstract

<b>OBJECTIVE.</b> The role of ¹⁸F-FDG PET/CT in the evaluation of recurrent salivary gland tumors remains poorly defined. We investigated the diagnostic and prognostic utility of PET in this setting. <b>MATERIALS AND METHODS.</b> A total of 146 patients with recurrent salivary gland cancer were treated at our institution between January 2002 and December 2015. Patients who underwent FDG PET/CT and conventional imaging (CT or MRI) within 3 months of recurrence (<i>n</i> = 78) were included in this retrospective analysis. On FDG PET/CT, we measured the SUV_max, total body metabolic tumor volume of all lesions, and total lesion glycolysis of all lesions to determine the intensity and extent of FDG-avid disease. We assessed the correlation of FDG PET/CT findings with clinicopathologic features, progression-free survival, and overall survival. <b>RESULTS.</b> FDG PET/CT was positive for recurrence in 74 of 78 patients (94.9%) and falsely negative in four patients (5.1%). In comparison with conventional imaging, FDG PET/CT performed for restaging detected additional recurrent lesions in 14 patients (17.9%). The median SUV_max was 7.4, the median total body metabolic tumor volume was 30.1 cm³, and median total lesion glycolysis was 97.3 g/mL × cm³. Sixty-six patients had progressive disease, and 54 died. Univariate and multivariate Cox hazards analysis identified pathologic risk group (<i>p</i> = .04), total body metabolic tumor volume (<i>p</i> < .001), and total lesion glycolysis (<i>p</i> < .001) as independent prognostic factors for progression-free survival and identified age (<i>p</i> = .05), total body metabolic tumor volume (<i>p</i> < .001), and total lesion glycolysis (<i>p</i> < .001) as independent prognostic factors for overall survival. <b>CONCLUSION.</b> In patients with recurrent salivary gland cancer, FDG PET/CT is useful as a single test for defining the extent of disease and providing prognostic information, which may help in selecting appropriate treatment strategies.