Survival curves of 233 newly diagnosed patients with ENKTL according to risk stratification. Group 1, low-risk limited disease (without risk factor); Group 2, high-risk limited disease (with at least one risk factor: male, poor performance status, higher LDH); Group 3, extensive disease with AA stage I-II; and Group 4, extensive disease with AA stage III-IV.

Note: ^a Patients treated without chemotherapy, with non-asparaginase-based chemotherapy and with asparaginase-containing chemotherapy were assigned the value 1, 2 and 3, respectively. A larger value of likelihood ratio 2 and a smaller value of −2 log likelihood indicated a better model for predicting outcome. CSWOG, Chinese Southwest Oncology Group; DLN, distant lymph node; LDH, lactic dehydrogenase; RLN, regional lymph node; TNM, Tumor-Node-Metastasis.