3.1. Patient characteristics
Ann Arbor stage
Totally, 829 suitable patients were initially identified from the SEER database, they were carefully screened and finally, 602 patients with H&NNHL were included in this study (255 patients were excluded due to unknown Ann Arbor stage, with further 2 patients rejected due to ambiguous pathological diagnosis [Fig. Research flowchart.The median survival time was 62 months, 27.4% of patients died from H&NNHL itself and the mortality of overall data was 58.8%. The socio-demographic and clinicopathologic characteristics of the patients are presented in Table Socio-demographic and clinicopathologic characteristics of 602 eligible patients.