While CAIX expression alone has proven to be an unreliable independent marker of tumor hypoxia [7], [33], [34], [37], the combined expression of CAIX and HIF-1α was significantly predictive of a worsened prognosis for HNSCC patients [14], [16], [18], [30], [35], [38]. The gene discussed is CA9; the disease is head and neck squamous cell carcinoma.