The first Part: recruiting untreated ENKL patients with extensive stage I or limited stage II disease (only referring to patients with the invasion of Waldeyer's ring and cervical lymph nodes) . Patients are randomly divided into two arms, IPGDP regimen chemotherapy followed by radiotherapy or radiotherapy followed by IPGDP regimen chemotherapy. IPGDP regimen for both arms are 3 cycles. And the chemotherapy is repeated every 3 weeks..

The second part: recruiting extensive stage II ,stage III-IV, relapsed or refractory ENKL patients. Patients receive 6 cycles of IPGDP regimen chemotherapy. And the chemotherapy is repeated every 3 weeks.

The first Part: Patients in IPGDP regimen chemotherapy followed by radiotherapy arm receive 3 cycles of IPGDP (ifosfamide 1.2g/m2 iv on days 3-5; pegaspargase 2000U/m2 im on day 1; gemcitabine 800mg/m2 iv on days 3,8; cisplatin 25 mg/m2 iv on days 3-5; dexamethasone 20mg/m2 iv on days 3-6) chemotherapy. Then patients undergo radiotherapy. If the disease is considered to progress or as stable during chemotherapy, the patient will directly receive radiotherapy. Patients in another arm receive radiotherapy followed by IPGDP regimen chemotherapy. IPGDP regimen for both arms are 3 cycles, which is repeated every 3 weeks.

The second Part: Patients receive 6 cycles of ifosfamide 1.2g/m2 iv on days 3-5; pegaspargase 2000U/m2 im on day 1; gemcitabine 800mg/m2 iv on days 3,8; cisplatin 25 mg/m2 iv on days 3-5; dexamethasone 20mg/m2 iv on days 3-6. IPGDP regimen is repeated every 3 weeks. If the disease is considered to progress or as stable after 2 cycles or 4 cycles of chemotherapy, the patient will withdraw from this study.

Inclusion Criteria:

• histologically proven diagnosis of Extranodal Natural Killer/T-Cell Lymphoma, Nasal Type(ENKL)
• untreated ENKL patients of extensive stage I and limited stage II ( only referring to patients with the invasion of Waldeyer's ring and neck lymph node) confirmed by imaging examination; extensive stage II ,stage III-IV, relapsed or refractory ENKL patients confirmed by imaging examination
• age 18-65 years
• at least one measurable lesions
• Eastern Cooperative Oncology Group (ECOG) of 0 to 1
• a life expectancy of at least 12 weeks
• Adequate organ function including the following:

Bone marrow: absolute neutrophil count (ANC) >or equal to 1.5 * 109/L, platelets >or equal to 100 *109/L, hemoglobin > or equal to 9g/dL.

Hepatic: bilirubin < or equal to 2 x ULN; aspartate transaminase (AST) and alanine transaminase (ALT) < or equal to 2.5 x ULN (AST, ALT < or equal to 5 x ULN is acceptable if liver has been involved).

Renal: serum creatinine < or equal to 1.5 x ULN. Coagulation function :activated partial thromboplastin time < or equal to 1.5 x ULN, fibrinogen > or equal to 0.75 times of the lower limit of the normal value, INR < or equal to 1.5 x ULN.

• informed consent signed by patients prior to commencement of the study
• pregnancy test of Women of childbearing must be negative at the beginning of 7 days before treatment; surgical sterilization or taking contraceptive measures during treatment and three months after the end of treatment for males.

Exclusion Criteria:

• severe allergies to the investigational drugs
• patients who had received unauthorized drugs or drugs of other trials within 4 weeks prior to the study
• Severe or unstable systemic disease，serious neurological or psychiatric diseases including seizures or dementia
• organ function including the following: Bone marrow: absolute neutrophil count (ANC) < 1.5 * 109/L, platelets<100 *109/L, hemoglobin < 9g/dL.

Hepatic: bilirubin > 2 x ULN; aspartate transaminase (AST) and alanine transaminase (ALT) >2.5 x ULN (AST, ALT > 5 x ULN is acceptable if liver has been involved).

Renal: serum creatinine > 1.5 x ULN. Abnormal Coagulation function : such as activated partial thromboplastin time prolonged > 1.5 x ULN, fibrinogen < 0.75 times of the lower limit of the normal value, increased INR > 1.5 x ULN any other important clinical or laboratory abnormalities that are not appropriate for research

• Patients who had previously received treatment of this study, or withdrew from the study
• receiving any other anti-tumor therapy at the same time
• pregnancy or lactation