Background:Nasal-type extranodal natural killer/T-cell lymphoma(ENKTCL) originates primarily in the nasal cavity or extra-nasal sites within the upper aerodigestive tract.However,it is unclear whether the primary site can serve as an independent prognostic factor or whether the varying clinical outcomes observed with different primary sites can be attributed merely to their propensities of regional lymph node involvement.The aim of this study was to investigate the prognostic implications of the primary site and regional lymph node involvement in patients with early-stage nasal-type ENKTCL.Methods:To develop a nomogram,we reviewed the clinical data of 215 consecutively diagnosed patients with early-stage nasal-type ENKTCL who were treated in Sun Yat-sen University Cancer Center with chemotherapy and radiotherapy between 2000 and 2011.The predictive accuracy and discriminative ability of the nomogram were determined using a concordance index(C-index) and calibration curve.Results:The 5-year overall survival(OS) and progression-free survival(PFS) rates of patients with nasal ENKTCL were higher than those of patients with extra-nasal ENKTCL(OS:68.2%vs.46.0%,P = 0.030;PFS:53.4%vs.26.6%,P = 0.010).The 5-year OS and PFS rates of patients with Ann Arbor stage IE ENKTCL were higher than those of patients with Ann Arbor stage HE ENKTCL(OS:66.3%vs.59.2%,P = 0.003;PFS:51.4%vs.40.3%,P = 0.009).Multivariate analysis showed that age >60 years,ECOG performance status score >2,elevated lactate dehydrogenase(LDH) level,extranasal primary site,and regional lymph node involvement were significantly associated with lower 5-year OS rate;age >60 years,elevated LDH level,extra-nasal primary site,and regional lymph node involvement were significantly associated with lower 5-year PFS rate.The nomogram included the primary site and regional lymph node involvement based on multivariate analysis.The calibration curve showed good agreement between the predicted and actual 5-year OS and PFS rates,and the C-indexes of the nomogram for the OS and PFS rates were 0.697 and 0.634,respectively.Conclusions:The primary site and regional lymph node involvement are independent prognostic factors for earlystage ENKTCL treated with chemotherapy followed by definitive radiotherapy. Background: Nasal-type extranodal natural killer / T-cell lymphoma (ENKTCL) originates to the nasal cavity or extra-nasal sites within the upper aerodigestive tract. However, it is unclear whether the primary site can serve as an independent prognostic factor or whether the varying clinical outcomes observed with different primary sites can be attributed merely to their propensities of regional lymph node involvement. The AIM of this study was to investigate the prognostic implications of the primary site and regional lymph node involvement in patients with early-stage nasal -type ENKTCL.Methods: To develop a nomogram, we reviewed the clinical data of 215 consecutively diagnosed patients with early-stage nasal-type ENKTCL who were treated in Sun Yat-sen University Cancer Center with chemotherapy and radiotherapy between 2000 and 2011. predictive accuracy and discriminative ability of the nomogram were determined using a concordance index (C-index) and calibration curve. Results: The 5- year overall survival (OS) and progression-free survival (PFS) rates of patients with nasal ENKTCL were higher than those of patients with extra-nasal ENKTCL (OS: 68.2% vs.46.0%, P = 0.030; PFS: 53.4% ​​vs .26.6%, P = 0.010). The 5-year OS and PFS rates of patients with Ann Arbor stage IE ENKTCL were higher than those of patients with Ann Arbor stage HE ENKTCL (OS: 66.3% vs. 59.2%, P = 0.003 ; PFS: 51.4% vs.40.3%, P = 0.009) .Multivariate analysis showed that age> 60 years, ECOG performance status score> 2, elevated lactate dehydrogenase (LDH) level, extranasal primary site, and regional lymph node involvement were significantly associated with lower 5-year OS rate; age> 60 years, elevated LDH level, extra-nasal primary site, and regional lymph node involvement were associated with lower 5-year PFS rate.The nomogram included the primary site and regional lymph node involvement based on multivariate analysis. The calibration curve showed good agreement between the predicted and actual 5-year OS and PFS rates, and the C-indexes of the nomogram for the OS and PFS rates were 0.697 and 0.634, respectively. Conclusions: The primary site and regional lymph node involvement are independent prognostic factors for early stage ENKTCL treated with chemotherapy followed by definitive radiotherapy.