CD44 and cancer: In a multicentre biomarker study of the German Cancer Consortium Radiation Oncology Group (DKTK‐ROG), CD44 protein expression has been shown to be a prognostic biomarker in patients with locally advanced HNSCC after primary radiochemotherapy (Linge et al., 2016b) as well as after oncological resection followed by postoperative radiochemotherapy (Linge et al., 2016a), with CD44 high expressing tumours being at high risk for tumour recurrence.