Comparison of OS and PFS between RT and CT alone. OS (A) and PFS (B) for patients with early-stage NKTCL after CT alone, RT alone, and RT with or without CT (RT w/o RT) before match stratification; OS (C) and PFS (D) after RT alone and CT alone after match stratification; and OS (E) and PFS (F) after RT with or without CT and CT alone after match stratification.