Fig. 1. Kaplan–Meier survival analysis. A and B: The 2-year and 5-year progression-free survival (PFS) rate 40.0% and 21.8%, respectively (A). The 2-year and 5-year overall survival (OS) rate 76.7% and 47.9%, respectively (B). C and D: Adjuvant radiotherapy showed statistically meaningful result in both PFS (C) and OS (D).