The purpose of this study is to evaluate the efficacy and safety of methotrexate, etoposide, pegaspargase and dexamethasone (MEDA) chemotherapy and autologous hematopoietic stem cell transplantation (Auto-HSCT) in patients with stage IV extranodal natural killer/T-cell lymphoma, nasal type.

Extranodal natural killer/T-cell lymphoma (ENKTCL), nasal type, is a rare subtype of non-Hodgkin lymphoma (NHL) with relatively high incidence in China. L-asparaginase based chemotherapy improved overall response and prolonged the long-term survival for patients with stage IV. But the optimal treatment schedule has not been established. This study is designed with four cycles MEDA chemotherapy, followed by Auto-HSCT for stage IV patients with newly onset, relapsed or refractory diseases. The efficacy and safety of this protocol in the treatment of will be measured.

Inclusion Criteria:

Pathological diagnosis of extranodal natural killer/T-cell lymphoma, nasal type based on WHO 2008 classification of tumors of haematopoietic and lymphoid tissue.

Eastern Cooperative Oncology Group (ECOG ) performance status 0~3.

Stage IV disease with at least one measurable lesion.

Preserved organ functions for: Platelet>50×10*9/L, hemoglobin>80g/L, total bilirubin (TBIL)<3×ULN, alanine transaminase (ALT)<5×ULN, serum creatinine (Cr)<1.5×ULN, fibrinogen≥0.5g/L, LVEF≥50%.

Signed Informed consented.

Exclusion Criteria:

Relapsed or progressive disease to prior L-asparaginase-based chemotherapy.

Concurrent cancers need surgery or chemotherapy within 6 months.

History of chemotherapy or radiotherapy for other solid cancers within 3 years.

Recent history of radiotherapy of upper-aero-digestive tract within last 3 months.

Significant complications: LVEF≤50%, coagulopathy, autoimmune disease, severe infection, or liver cirrhosis, severe hemophagocytic lymphohistiocytosis.

Mental disorders.

Pregnant or lactation.

HIV, hepatitis virus C (HCV), or active hepatitis virus B (HBV) infection with HBV DNA≥10*5 copies/ml.

History of pancreatitis.

Known history for grade 3/4 allergy to the drugs in chemotherapy regimen.

Enrolled in other trial treatment.