Pegaspargase-COEP Chemotherapy Combined With Radiotherapy for Extra-nodal NK/T Cell Lymphoma

Inclusion Criteria: * patients with confirmed pathological diagnosis of ENKTL as defined by WHO criteria * age 14-80 years * no prior chemotherapy or radiotherapy * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 * at least one measurable lesion * adequate bone marrow function (i.e. hemoglobin ≥80 g/l, absolute neutrophil count ≥ 1.0 × 10\^9/L, platelets ≥ 100 ×10\^9/L), adequate renal function (i.e. serum creatinine ≤177 μmol/L), adequate hepatic function (e.g. total bilirubin ≤ two times the upper limit of normal, and ALT /AST ≤2.5 times the upper limit of normal) * expected survival of more than three months Exclusion Criteria: * invasion of lymphoma to central nervous system * pre-existing coagulation disorder * other concomitant neoplasms * severe infection * positive HIV antibody * HBV DNA titer higher than 10\^4 copies /ml in HBsAg-positive patients post antiviral therapy * pregnant or lactating women * women of childbearing age unwilling to take contraceptive measures during the study period