Short-Course Versus Long-Course Chemoradiotherapy for Stage IE-IIE Extranodal Natural Killer/T cell Lymphoma, Nasal Type: A Multicenter Retrospective Study.

BACKGROUND This study compared clinical outcomes and adverse events between L-asparaginase/pegaspargase-based short-course and long-course chemoradiotherapy in newly diagnosed stage IE-IIE extranodal natural killer/T cell lymphoma, nasal type (ENKTL). MATERIAL AND METHODS Patients were categorized into a short-course (2-4 chemotherapy cycles, median: 4, n=153) and long-course group (5-6 cycles, median: 6, n=83). The chemotherapy regimens included GELOX, SMILE, and VLP. The radiotherapy dose was 40-63 Gy (median: 55 Gy). Adverse events, treatment responses, and survival outcomes between the 2 groups were compared. RESULTS Ann Arbor stage IIE and short-course chemotherapy adversely affected overall survival (OS). Ann Arbor stage IE favorably affected progression-free survival (PFS). Grade 3-4 hematological toxicities were higher in the long-course group (25.3% vs. 14.4%, p=0.038). Ann Arbor stage was the single different clinical feature between the 2 groups, and independently affected survival outcomes. In subgroup analysis of stage IE, there was no difference in response rates and survival outcomes between the 2 groups. In subgroup analysis of stage IIE, the recurrence and death rates were significantly lower in the long-course group (6.1% vs. 23.2%, p=0.015; 12.2% vs. 39.3%, p=0.002; respectively), and the 3-year OS and PFS rates were much longer in the long-course group (87.8% vs. 62.5%, p<0.001; 83.7% vs. 57.1%, p=0.001; respectively). CONCLUSIONS When radiotherapy was combined with L-asparaginase/pegaspargase-based chemotherapy to treat early-stage ENKTL patients, 2-4 cycles of chemotherapy might be sufficient for stage IE patients, while stage IIE patients might require 5+ cycles.