Kaplan-Meier estimates of survival according to p16 expression and treatment received. Panels A and B show OS and DFS, respectively, for p16-positive patients according to the treatment received. Patients with p16-positive tumors treated with RT+EGFR inhibitors had significantly better OS and DFS than those treated with RT+CT (p = 0.01 for both comparisons by the two-sided log-rank test). Panels C and D show OS and DFS, respectively, for p16-negative patients according to the treatment received. No benefit in OS or DFS was observed in these patients when treated with RT+EGFR inhibitors compared to RT+CT (p = 0.9).