Extranodal natural killer/T-cell lymphoma (ENKTL) is an aggressive subtype of non-Hodgkin's lymphoma and shows extremely poor survival. Several retrospective studies and singe-arm prospective phase 2 studies have shown that pegaspargase combined Gemox or CHOP regimen achieved a promising efficacy in treatment of ENKTL. However, there is no prospective study to compare the efficacy of these two regimens. This prospective pilot study to compare the efficacy and safety of the P-Gemoxd chemotherapy regimen with those of the P-CHOP regimen for stage IE to IIE ENKTL.

Treatment PA-Gemoxd dosages were as follows: days 1 and 5, 30-min intravenous infusion of 800 mg/m2 gemcitabine; day 1, 2-h intravenous infusion of 85 mg/m2 oxaliplatin; day 1, deep intramuscular injection of 2000 U/m2 PEG-ASP at four different sites; d1-5, intravenous infusion of 15mg dexamethasone. The regimen was repeated every 3 weeks for four cycles followed by involved-field radiotherapy after got CR, PR or SD. Three-dimensional conformal radiotherapy was done by linear accelerator at 2.0 grays (Gy) per daily fraction with 5-6 weeks. The involved- field radiation (IFRT) dose was 50-56 Gy.

Inclusion Criteria:

1. pathologically confirmed, previously untreated ENKTL with stage I/II (for stage I, the patients should have one of the following risk factors: EBV-DNA > upper limit of normal, lesions beyond nasal, fever, LDH elevation);
2. age range from 18 to 70 years;
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0-2;
4. at least one measurable lesion;
5. adequate haematologic function (haemoglobin > 8.0 g/l, absolute neutrophil count > 1500/ml, platelets > 75,000/l),
6. adequate hepatic function (total serum bilirubin ≤ 1.5 times the upper limit of normal, alanine aminotransferase and aspartate aminotransferase ≤ 2.5 times the upper limit of normal),
7. Hepatitis B virus carriers should have normal HBV-DNA copies and should use antiviral drugs. For patients with elevated HBV-DNA, should use antiviral drugs until the HBV-DNA decrease to < the upper limit of normal.
8. adequate renal function (serum creatinine ≤ 1.5 mg/dl, creatinine clearance ≥ 50 ml/min);
9. normal coagulation function and electrocardiogram results.
10. Prior chemotherapy and radiotherapy should have been completed >4 weeks earlier,
11. willingness to provide written informed consent.

Exclusion Criteria:

1. mismatch the inclusion criteria
2. systematic central nervous system involvement, previous or concomitant malignancies and any coexisting medical problems that could cause poor compliance with the study protocol.
3. primary lesion not from the upper respiratory