Culture of HNSCC biopsies (5–10 mg) for 6 days was used to analyze the response of tissue to irradiation (2–40 Gy). Cell death was measured by detection of LDH in the effluent, and immunohistochemistry for cleaved cytokeratin-18 was used to calculate an apoptotic index. This evidence concerns the gene KRT18 and head and neck squamous cell carcinoma.