This study is to evaluate the efficacy of risk-adapted treatment strategy for stage I/II extranodal NK/T cell lymphoma. The risk stratification is based on the Korean NK prognostic index. Thus, the group I/II will receive concomitant chemoradiation followed by VIDL chemotherapy. The group III/IV will receive high dose-chemotherapy followed by autologous stem cell transplantation after the completion of VIDL chemotherapy.

1. Concomitant chemo-radiotherapy:

   Radiotherapy 36-44 Gy/18-22 fractions

   + weekly cisplatin 30 mg/m2 for 4 weeks

2. Rest period: 3 weeks

3. VIDL combination chemotherapy: (total 2 cycles) VP-16 (etoposide) 100mg/m2 I.V. D1-3 Ifosfamide 1.2g/m2 I.V. D1-3 Dexamethasone 40mg/day D1-3 L-asparaginase 4000IU/m2 IM D8, 10, 12, 14, 16, 18, 20 Repeated every 28 days

4. Peripheral blood stem cell mobilization G-CSF 400ug/m2/day or 10ug/kg/day S.C. or I.V. for 4-6 days followed by stem cell collection (Minimum requirement of CD34+ cells > 2×106/kg)

5. High-dose chemotherapy with autologous stem cell transplantation Busulfex 3.2mg/kg/day from day -7 to day -5 Etoposide 400mg/m2/day on day -5, -4 Cyclophosphamide 50mg/kg/day on day -3, -2 Followed by stem cell infusion

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.

6 months after registration

We applied the same definition as the clinicaltrials.gov.

Concomitant Chemo-radiotherapy Plus VIDL Chemotherapy