HIF1A and oral cavity squamous cell carcinoma: The definition of BTV combining 18F-FDG-PET and contrast-CT is not the most robust way to define the hypoxic segment, even if is capable of defining more aggressive tumor types correlated with HIF-1a expression in patients with gastric [39], tongue [40], NSCLC [41, 42], and oral squamous cell carcinoma [40–43].