Optimal Courses of Chemotherapy Combined with Radiotherapy for Low-Risk Extranodal Natural Killer/T-Cell Lymphoma, Nasal Type: A Propensity Score Matching Analysis

Purpose: This retrospective study compared effectiveness between <= 4 cycles and >= 5 cycles of L-asparaginase/pegaspargase-based chemoradiation in newly diagnosed low-risk extranodal natural killer/T-cell lymphoma (ENKTL), nasal type classified according to the Prognostic Index of Natural Killer (PINK) lymphoma model. Patients and Methods: Patients were categorized into <= 4-cycle (2-4 chemotherapy cycles, n = 166) and >= 5-cycle groups (5-6 cycles, n = 86). Propensity score matching analysis was used to reduce potential confounding bias between the two groups. Treatment responses, adverse events, and survival outcomes between the two groups were analyzed. Results: No matter before or after matching (65 in the <= 4-cycle group, 65 in the >= 5-cycle group), response rates and survival outcomes were similar between the <= 4-cycle and >= 5-cycle groups. Incidences of grade 1-2 anemia and transaminase elevation were higher in the >= 5-cycle group. After matching, for stage IE disease, there were no differences in response rates and survival outcomes between the two groups. For stage IIE disease, the complete response rate was higher in the >= 5-cycle group (72.4% vs 92.6%, p = 0.049), and the 3-year overall survival (65.5% vs 85.2%, p = 0.024) and 3-year progression-free survival (58.6% vs 81.5%, p = 0.027) rates were significantly extended in the >= 5-cycle group. Conclusion: When chemoradiotherapy strategies with L-asparaginase/pegaspargase-based regimens are applied to modem low-risk ENKTL patients classified according to the PINK model, it may be better to moderately extend chemotherapy courses in patients with stage IIE disease.