Severe acute and chronic dysphagia, SAD and SCD, respectively, are side effects of radio(chemo)therapy for head-and-neck cancer. The project aims at refining and validating of the SAD biomarker, developing a SCD biomarker and their testing in preventive therapeutic intervention. Both biomarkers are constructed by multivariate logistic regression using predictor-variables reflecting the injury-causing treatment and the susceptibility of the individual patient.