Fig. 2

Kaplan–Meier curves stratified by surgery. Y-axis label “Survival probs” means survival probabilities. a, b Kaplan–Meier curves among unmatched patients stratified by surgery types for all-cause death (a, Log rank test p < 0.0001) and nasopharyngeal carcinoma-specific death (b, Log rank test p = 0.0003). c, d Kaplan–Meier curves among matched patients stratified by surgery/non-surgery for all-cause death (c, Log rank test p = 0.0685) and nasopharyngeal carcinoma-specific death (d, Log-rank test p = 0.0605). e, f Kaplan Meier curves among matched patients stratified by surgery type local tumor excision and pharyngectomy for all-cause death (e, Log rank test p = 0.3502) and nasopharyngeal carcinoma-specific death (f, Log-rank test p = 0.3679)