Löck S, et al. – In order to assess the residual tumour hypoxia in head–and–neck cancer patients undergoing primary radiochemotherapy, experts conducted this study. As per findings, residual tumour hypoxia during radiochemotherapy was a major driver of therapy resistance of head and neck squamous cell carcinoma (HNSCC). This study validated that hypoxia after the second week of treatment measured by [18F]fluoromisonidazole positron emission tomography (FMISO–PET) appeared to serve as a biomarker for selection of patients at high risk of loco–regional recurrence after state–of–the art radiochemotherapy.