Objective: Extranodal natural killer/T cell lymphoma (ENKTCL) is one type of non-Hodgkin's lymphomas. It's highly malignant and aggressive. The survival rate of patients with ENKTCL is low and the prognosis is extremely pessimistic. With regard to the common therapeutic regimen, there is no absolute answer. Thus, this research aims to retrospectively analyze clinical features, efficacy and prognosis based on the data of ENKTCL patients from two different clinical centers, so as to provide real-world evidence for the clinical treatment of the disease. Methods : Clinical data of 18 ENKTCL patients treated in Hematological Department of Zhongda hospital Southeast University from January 2013 to December 2022 and 104 ENKTCL patients from Jiangsu Cancer Hospital from January 2017 to December 2022 were retrospectively collected. Clinical data included age at initial diagnosis, gender, stage, clinical classification, B symptom, number of extranodal involvement sites, the situation of regional lymph nodes involvement, the situation of bone marrow involvement, KPS, ECOG, PINK, NRI, immunohistochemistry, the clinical symptom, therapy regimen, laboratory and imaging test. Then analysis of efficacy and prognosis was done. Follow-up was conducted by telephone contact with the patient and/or family until April 2023. Results: 1. Among the different treatment options, the efficacy of a combination of chemotherapy with radiotherapy group was statistically significant compared with either single chemotherapy group (P=0.000) or single radiotherapy group (P= 0.009) for patients with limited-stage disease (stage I/II), but there was no significant difference in the efficacy between chemotherapy group and radiotherapy group (P>0.05).Similarly, the efficacy of chemotherapy with radiotherapy group was statistically higher than that of single chemotherapy group (P=0.012), and that of a combination of chemotherapy with targeted therapy group was statistically higher compared with single chemotherapy group (P= 0.041) for patients with advanced-stage disease (stage III/IV), but there was no statistical difference between the single chemotherapy group and its combination with radiotherapy and targeted therapy group, the combination of chemotherapy with radiotherapy group and their combinations with targeted therapy group, the combination of chemotherapy with targeted therapy group and their combinations with radiotherapy group (All P >0.05). For all patients receiving chemoradiotherapy, there was no statistical significance in the efficacy of the sequential chemoradiotherapy group compared with the sandwich chemoradiotherapy group (P=0.547). 2. Univariate analysis showed that age at initial diagnosis, stage, presence of B symptoms, lactate dehydrogenase (LDH), ECOG score, extranodal involved site and number, and therapy regimen were factors related to the prognosis of patients (All P<0.05). Multivariate analysis further showed that patients' age at initial diagnosis, LDH, ECOG score and therapy regimen were the main factors affecting the prognosis of ENKTCL patients (P<0.05). Conclusion: 1. In the treatment scheme of ENKTCL, the combination of radiotherapy and chemotherapy has a better effect for patients at stage I and II, whereas chemotherapy should be combined with radiotherapy or targeted therapy to improve the efficacy of patients at advanced stage III and IV. For all patients with chemoradiotherapy, the efficacy of sequential chemoradiotherapy is similar to sandwich chemoradiotherapy. 2. The age at initial diagnosis, LDH, ECOG score and therapy regimen are the main factors affecting the prognosis of ENKTCL patients.