The purpose of this multi-center, single arm, phase Ⅱ clinical trail is to evaluate the efficacy and toxicity of concurrent chemoradiotherapy by using single-drug pegaspargase for patients with ENKTL in stage IE to IIE.

The treatment regimen included CCRT ( involved field radiotherapy 50GY, concurrent 2 cycles of pegaspargase treatment ) followed by 4 cycles of pegaspargase. Chemotherapy and RT were performed simultaneously within one week after enrollment. The administration regimen was as follows : day1, deep intramuscular injection of 2500 unit/m2 pegaspargase at three different sites, and repeated once every 3 weeks. 3D conformal radiotherapy was performed using 4 or 6 MV photons generated by a linear accelerator. The radiation dose was 50 Gy, 2.0 Gy / time, 1 time / d, for 5 weeks. The clinical target volume ( CTV ) of limited stage IE patients was defined as bilateral nasal cavity, bilateral ethmoid sinus and ipsilateral maxillary sinus. The CTV of extensive stage IE patients was extended to the affected tissues. The CTV of stage IIE lesions also included the involved cervical lymph node area.

Inclusion Criteria:

1.The patient was pathologically diagnosed as ENKTL and had not received any previous treatment for ENKTL;2.The estimated survival time ≥ 3 months. 3.18-75 years old ; 4. Ann-Arbor stage was IE-IIE ; 5. ECOG performance status 0-2 ; 6.Clinicians judged that patients were suitable for concurrent chemoradiotherapy ; 7.No radiotherapy or hormone drugs were received within 4 weeks before treatment;8.After the patients were enrolled in the trial, they could not accept other drugs that may have therapeutic effects on ENKTL ; 9.WBC≥ 3 × 109 / L, NE ≥ 1.5 × 109 / L, PLT ≥ 100 × 109 / L ; 10.Serum creatinine ≤ 1.5mg / dL, creatinine clearance rate ≥ 50mL / min ; 11.ALT, AST ≤ 3 × ULN ( normal upper limit ) ; total bilirubin ≤ 2 × ULN ; 12.Serum fibrinogen level ≥ 1.0g / L ; 13.Signed informed consent form.

Exclusion Criteria:1.Symptomatic CNS involvement, previous or current accompanied by other malignant tumors ; 2.The primary lesion is ENKTL from non-upper respiratory gastrointestinal tract ; 3.Patients with poor general condition, ECOG performance status >2 ; 4.Women in pregnancy or lactation; 5.The patient ( male or female ) has the possibility of fertility but is unwilling or does not take effective contraceptive measures; 6. Known allergies to test drugs or any excipient component of these products ;7.Doctors believe that patients are not suitable for concurrent chemoradiotherapy; 8.Active infection ( determined by the researcher ) ; 9.According to the researchers ' judgment, there are concomitant diseases that seriously endanger the safety of patients or affect the completion of the study;10. Have a clear history of neurological or psychiatric disorders, including epilepsy or dementia.