This study evaluated the survival benefit of intensity-modulated radiation therapy (IMRT) compared with 3-dimension conformal radiation therapy (3D-CRT) in a large national cohort of patients with early-stage extranodal nasal-type natural killer/T-cell lymphoma (NKTCL). This retrospective study reviewed patients with early-stage NKTCL treated with high-dose radiation therapy (RT; ≥45 Gy) at 16 Chinese institutions. Patients were stratified into 1 of 4 risk groups based on the number of risk factors: low risk (no factors), intermediate-low risk (1 factor), intermediate-high risk (2 factors), and high-risk (3-5 factors). Of the 1691 patients, 981 (58%) received IMRT, and 710 (42%) received 3D-CRT. Unadjusted 5-year overall survival (OS) and progression-free survival (PFS) were 75.9% and 67.6%, respectively, for IMRT compared with 68.9% (P = .004) and 58.2% (P < .001), respectively, for 3D-CRT. After propensity score match and multivariable analyses to account for confounding factors, IMRT remained significantly associated with improved OS and PFS. The OS and PFS benefits of IMRT persisted in patients treated with modern chemotherapy regimens. Compared with 3D-CRT, IMRT significantly improved OS and PFS for high-risk and intermediate-high-risk patients but provided limited benefits for low-risk or intermediate-low-risk patients. A risk-adapted survival benefit profile of IMRT can be used to select patients and make treatment decisions.
© 2018 by The American Society of Hematology.