Prognostic Values of TIGAR Expression and (18)F-FDG PET/CT in Clear Cell Renal Cell Carcinoma

Aim: Evaluation of (18)F-FDG accumulation using PET/CT is an potential imaging biomarker to reflect tumor metabolic burdens and to help predict prognosis in renal cell carcinoma (RCC). p53-induced glycolysis and apoptosis regulator (TIGAR) is a protein regulates glycolytic activity and glucose metabolism. The deregulated TIGAR expression has been associated with tumorigenesis and poor disease prognosis in several cancers. The purpose of this study is to evaluate the impact of the TIGAR expression and the maximum standardized uptake value (SUVmax) of (18)F-FDG PET/CT on survival for patients with clear cell RCC. Methods: A total of 62 patients with confirmed clear cell RCC were included in this retrospective study. The TIGAR expression of tumors were determined through immunohistochemistry staining. The SUVmax of clear cell RCC lesions were assessed using (18)F-FDG PET/CT. The impact of TIGAR expression and SUVmax on overall survival was evaluated by the Cox proportional hazards model and the Kaplan-Meier survival analysis. Results: Increased TIGAR staining was associated in clear cell RCC patients with older age, venous tumor thrombus, or increased SUVmax. A positive correlation was found between TIGAR expression and SUVmax in patients (r=0.396, P=0.001). Patients with positive TIGAR expression had a decreased overall survival time than those with negative TIGAR expression. The overall survival time was significantly shorter in patients with high SUVmax (>5.25) compared with those with low SUVmax (≤5.25). SUVmax and Fuhrman grade were identified as independent prognostic factors in clear cell RCC. Patients with high SUVmax (>5.25) and positive TIGAR expression were associated with a worse disease prognosis. Conclusion: The expression of TIGAR is significantly correlated with SUVmax in clear cell RCC. The combined use of TIGAR expression and (18)F-FDG PET/CT can provide additional information for tumor glucose metabolic status and disease prognosis in patients with clear cell RCC.