Does improved locoregional control translate into a survival benefit in patients with early-stage extranodal natural killer/T-cell lymphoma (NKTCL)?
In a cohort study of 1332 patients in China with early-stage NKTCL, radiotherapy had a dose-dependent association with locoregional control, progression-free survival, and overall survival. Improved locoregional control was associated with prolonged progression-free survival and overall survival.
Clinicians and patients should be aware of the essential role of radiotherapy in both locoregional disease control and maintaining long-term survival.
The long-term survival benefit for radiotherapy (RT) in early-stage extranodal natural killer/T-cell lymphoma (NKTCL) is not known, and it is unclear whether improved locoregional control (LRC) translates into a survival benefit.
To investigate the dose-dependent effect and potential survival benefits of RT on the basis of LRC improvements.
Design, Setting, and Participants
Review of clinical data of patients with early-stage NKTCL at 10 institutions in China between 2000 and 2014. Radiotherapy dose as a continuous variable was entered into the Cox regression model by using penalized spline regression to allow for a nonlinear relationship between RT dose and events. Regression analysis was used to assess whether a linear correlation exists between LRC and progression-free survival (PFS) or overall survival (OS). Patients received chemotherapy (CT) alone, RT alone, or a combination. Chemotherapy alone was defined as 0 Gy.
Main Outcomes and Measures
The association between LRC and OS or PFS.
A total of 1332 patients (923 [69%] male; median age, 43 years [range, 2-87 years]) were reviewed. For patients treated with RT, median dose was 50 Gy (range, 10-70 Gy); 996 (86%) received at least 50 Gy, and 164 (14%) received 10 to 49 Gy. The risk of locoregional recurrence, disease progression, and mortality decreased sharply until 50 to 52 Gy. For patients receiving RT, high-dose RT (≥50 Gy) was associated with significantly better 5-year LRC (85% vs 73%; P < .001), PFS (61% vs 50%; P = .004), and OS (70% vs 58%; P = .04) than low-dose RT (<50 Gy). Improved LRC with high-dose RT was independent of the RT/CT sequence or initial response to CT. Radiotherapy yielded a dose-dependent effect on LRC (range, 41%-87%), PFS (18%-63%), and OS (33%-71%). Dose-response regression analysis revealed a linear correlation between 5-year LRC and 5-year PFS (correlation coefficient, r = 0.994, P < .001; determination coefficient, R2 = 0.988) or 5-year OS (r = 0.985, P = .002; R2 = 0.97), which was externally validated using published data.
Conclusions and Relevance
The optimal dose was 50 Gy for patients with early-stage disease. The improved LRC was associated with prolonged survival. These findings emphasize the importance of RT in optimizing first-line therapy, and provide evidence for making treatment decisions and designing clinical trials.
Yang Y, Cao J, Lan S, Wu J, Wu T, Zhu S, Qian L, Hou X, Zhang F, Zhang Y, Zhu Y, Xu L, Yuan Z, Qi S, Li Y. Association of Improved Locoregional Control With Prolonged Survival in Early-Stage Extranodal Nasal-Type Natural Killer/T-Cell Lymphoma. JAMA Oncol. 2017;3(1):83–91. doi:10.1001/jamaoncol.2016.5094