CD-44 has been found as a surface marker of Cancer Stem Cells (CSCs), a distinctive subpopulation of cancer cells implicated in tumour initiation, invasion, recurrence, and resistance to chemo-radiotherapy41: in this context, CD-44 correlates with local tumour control after RT of early laryngeal cancer, lung adenocarcinoma, oropharyngeal squamous cell carcinoma and pancreatic cancer as its expression bears the potential to predict the RT outcome by assessment of CSCs density42–48. The gene discussed is CD44; the disease is cancer.