Fig. 1

a–h Kaplan-Meier plots for different prognostic factors. The overall survival is shown in a, c, d, e, f and h, in b the disease-free survival, and in g the relapse-free probability. The number of patients at risk is shown at the bottom of the figures. Significance levels were calculated with a log-rank test. a, b The whole study population, the shaded area shows the 95% confidence limits. c Age groups. d N stage. e Extracapsular tumor extension. f, g p16 status. h Treatment. Treatment A = neck dissection and postoperative radiation, treatment B = (chemo) radiation, and treatment C = neck dissection