FDG-PET enables the clinical detection of glucose metabolism alteration in cancer and is used to predict initial staging, follow-up, clinical outcome, and second primary cancer screening of HNSCC [25, 26]. In addition, volumetric PET/CT parameters can predict a response to chemoradiation therapy in patients with HNSCC . Therefore, FDG-PET parameters can be used as predictive and prognostic markers. Moreover, PET of glutaminolysis in tumors has been studied to compensate for the shortcomings of FDG-PET . Thus, detecting cancer cell metabolism with nuclear imaging has been integrated into routine clinical application, and its application continuous to improve. In our study, the patients with stage I and II demonstrated the AST/ALT ratio was so low that analysis results were not significant (data not shown). This might reflect that above a certain level of the tumor volume with hypermetabolism is needed to cause a difference in the AST/ALT ratio. From the results of this study, we inferred that measuring of the AST/ALT ratio could substitute metabolic imaging in both its prognostic and predictive roles.