Salivary gland malignancies are unique in their histological and behavioral variability. Decisions on treatment regimens and prognostic prediction require evaluation of the histological diagnoses. Positron emission tomography (PET) using 18F-fluoro-2-deoxy-D-glucose (FDG), which reflects glucose metabolism, has been reported to be useful for the diagnosis of several malignancies. However, the clinical utility of 18F-FDG-PET in evaluating salivary gland malignancies has not been clarified.
In this study, we investigated the utility of FDG-PET in histologic grading and prognostic prediction for patients with salivary gland malignancies. To indicate the degree of 18F-FDG accumulation, the standardized uptake value (SUV) was used. High-grade malignancies had significantly higher mean maximum SUVs than did low- and intermediate-grade malignancies. In univariate survival analysis, the cumulative survival decreased as the SUV increased, when the maximum SUV of 7.8 was taken as a cut-off for high and low uptake tumors. We concluded that FDG-PET has a significant impact in histologic grading and prognostic prediction for patients with salivary gland malignancies.