CA9 and head and neck squamous cell carcinoma: Recently, Nicolay et al. in a prospective study have shown the association of tumour hypoxia markers—HIF1α and CA9—studied by IHC in pre-treatment biopsies with the hypoxia dynamics during chemoradiation assessed by 18F-FMISO PET/CT imaging in LA-HNSCC patients.46 In addition to hypoxia and angiogenic markers, other frequently altered downstream molecules of EGFR signalling, including the PI3K–AKT–mTOR pathway, need to be evaluated in combination for their predictive potential in HNSCCs.47,48