Varied survival benefit profile of IMRT vs 3D-CRT based on NKTCL-PI. Patients with early-stage NKTCL were stratified into 4 risk groups with different OS (A) and PFS (B). HRs for OS (C) and PFS (D) for IMRT vs 3D-CRT within different risk subgroups defined by NKTCL-PI. Forest plots showing improved OS (C) and PFS (D) for IMRT compared with 3D-CRT in patients at intermediate-high or high risk but limited benefit of IMRT in patients at low or intermediate-low risk.