Another study with 15 HNSCC patients did not show any correlation between immunohistochemical markers (including GLUT1 and HIF1a), FDG-PET parameters, and (18F)fluoroerythronitroimidazole [(18F)FETNIM]-PET, another hypoxia/perfusion tracer (56). Here, HIF1A is linked to head and neck squamous cell carcinoma.