Increased glucose metabolism by FDG-PET correlates with reduced tumor angiogenesis in oral squamous cell carcinoma

Hypoxia is known to have been related with angiogenesis and glycolysis, and may have an influence on tumor treatment effect. Because glucose utilization is higher in malignant cells than that in normal cells, dynamic glucose metabolism of tumor has been evaluated by means of [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET). To investigate the significance of tumor vascularization in oral squamous cell carcinoma, we compared tumor angiogenesis with the FDG-PET findings. Twenty patients underwent FDG-PET. For the quantitative evaluation of FDG uptake in each tumor, the mean standardized uptake value (SUV) was calculated. Microvessel structures labeled with CD34 antigen were investigated in pretreatment biopsy specimens. Using an image analyzer, we calculated the following microvessel parameters: the ratio of the total number of microvessels (TN) to tumor area (TA), the ratio of the total microvessel perimeter (TP) to the TA, and the ratio of the tumor tissue area more than 150 μm distant from each microvessel (hypoxic ratio, %). The SUV was compared with the above parameters. Simple regression analysis revealed a statistical significance between the SUV and the TN:TA ratio (p = 0.046), as well as between the SUV and the TP:TA ratio (p = 0.0206). The SUV was found to be inversely related to the TN:TA and TP:TA ratios. Elevated glucose metabolism assessed by FDG-PET correlated with reduced vascularization. Higher glucose metabolism might therefore reflect a state of hypoxia.