The purpose of this study is to evaluate the efficacy of concomitant chemoradiation followed by MIDLE chemotherapy for stage I/II extranodal NK/T cell lymphoma.

Concomitant chemo-radiotherapy:

Radiation 36-44 Gy/18-22 fractions (2 Gy/fraction) Weekly Cisplatin 30mg/m2 + N/S 100ml MIV over 30min Tri-weekly L-asparaginase 4000 IU IV (D1, 3, 5)

Rest period: 3 weeks

MIDLE chemotherapy: Repeated every 28 days for 2 cycles D1 Methotrexate 3g/m2 + D5W 500ml MIV over 6 hours D2-D3 Etoposide 100mg/m2 + D5W 500ml MIV over 90mins D2-D3 Ifosfamide 1000mg/m2 + D5W 100ml MIV over 1hr D2-D3 Mesna 300mg/m2 + D5W 100ml MIV over 15mins (-15min, 4hrs and 8hrs after ifosfamide, total 3 doses) D1-D4 Dexamethasone 40mg/d PO or IV D4, 6, 8, 14, 10 L-asparaginase 6000IU/m2 + D5W 500ml MIV over 2hours

Inclusion Criteria:

• patients were required to have a biopsy-proven diagnosis of nasal ENKTL
• at least 18 years old
• Ann Arbor stage IE or IIE
• measurable disease
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 life expectancy greater than 12 weeks
• adequate hematologic (hemoglobin > 9.0 g/dL, absolute neutrophil count > 1,500/uL and platelets > 100,000/uL)
• renal (serum creatinine < 1.5 mg/dL, creatinine clearance > 50 mL/min)
• hepatic (total bilirubin < 2 times of upper limit of normal and aspartate transferase < 3 times of upper limit of normal) function
• Diagnosis of ENKTL is based on the presence of histological features and immunophenotypes compatible with ENKTL (e.g., cytoplasmic CD3+, CD20-, CD56+,
• positive for cytotoxic molecules
• positive for EBV by in situ hybridization).
• Informed consent

Exclusion Criteria:

• prior or concomitant malignant tumors
• any coexisting medical problems of sufficient severity to prevent full compliance with the study protocol.
• ENKTL with non-nasal sites such as skin or gastrointestinal tract was excluded even if it is localized.
• Other subtypes of non-Hodgkin lymphoma (NHL), including myeloid/NK cell precursor acute leukemia, blastic NK cell lymphoma/precursor NK cell lymphoblastic leukemia, aggressive NK cell leukemia, and peripheral T cell lymphoma, unspecified, were excluded.