[The effects of sequence of radiotherapy and chemotherapy on prognosis of patients with early-stage extranodal NK/T cell lymphoma (nasal type) and its individualized application].

ABSTRACT

Objective: To analyze the effects of the sequence of radiotherapy and chemotherapy on the efficacy of early-stage extranodal NK/T-cell lymphoma (nasal type, ENKTCL) patients, and to provide a quantitative evaluation method for individualized radiotherapy and chemotherapy. Methods: The Chinese Lymphoma Collaborative Group (CLCG) collected the clinical data of 2 008 patients with early-stage Ⅰ/Ⅱ ENKTCL who received radiotherapy and chemotherapy from January 2000 to early September 2019 from 21 hospitals across the country, including 1 417 males and 591 females, aged 2 to 83 (42±14) years. According to the sequence of radiotherapy and chemotherapy, patients were divided into radiotherapy-first group (388 cases) and chemotherapy-first group (1 620 cases). Survival rate was estimated using Kaplan-Meier method, and multivariate Cox proportional risk model was used to screen and identify independent prognostic factors. The prognostic prediction models of the two therapies were constructed separately, and the models were used to predict the individualized mortality risk of all patients to determine the appropriate radiotherapy and chemotherapy regimen for each patient. Results: The 5-year overall survival rate was 74.2% (95%CI 69.6%-79.2%) in the radiotherapy-first group and 69.7% (95%CI 67.1%-72.4%) in the chemotherapy-first group. Although the 5-year overall survival rate of patients in the radiotherapy-first group was numerically higher than that of the chemotherapy-first group, the difference was not statistically significant (χ2= 2.26, HR=0.84 (95%CI 0.68-1.05), P=0.133). Six variables including age, gender, ECOG score, LDH, Ann Arbor staging, and PTI (primary tumor invasion) were screened out as independent prognostic factors (the chemotherapy-first group HR were 1.01, 1.25, 2.07, 0.77, 1.34, 1.49, respectively, all P<0.05; radiotherapy-first group HR were 1.02, 1.31, 1.66, 0.78, 1.37, 1.29, all P>0.05). The mean 5-year predicted mortality risk for all patients receiving radiotherapy-first regimen was lower than those receiving chemotherapy-first regimen (26.8% vs 30.2%, P<0.001). There were individualized differences in the predicted mortality risk of patients with different clinical characteristics who received radiotherapy-first regimen or chemotherapy-first regimen. Conclusion: Patients with stage Ⅰ/Ⅱ ENKTCL treated with radiotherapy-first regimen had a better expected prognosis than patients treated with chemotherapy-first regimen. The quantitative assessment of the differential effects of the sequence of radiotherapy and chemotherapy on the mortality risk of individual patients based on their clinical characteristics was helpful for the clinical development of the optimal radiotherapy and chemotherapy plan for each patient.