Although modern radiation techniques combined with chemotherapy has greatly improved the local control and long-term survivals for patients with early-stage NKTCL, relapse and systemic dissemination are common for localized patients. Relapsed/refractory diseases together with advanced stage NKTCLs uaually progress rapidly with poor prognosis (5-year overall survival rate, 0-20%). According to published studies, some recurrent genetic alternations have been identified in NKTCL, including oncogene/tumor suppressive gene abberants, epigenetic changes, cellular signaling pathways abnormalities, cellular apoptosis related genes and so forth. However, the gene profiling techniques and materials vary in different studies, no consensus has been reached on the gene abnormalities of advanced, or relapsed/refractory NKTCL up to now. Additionally, gene sequencing using ctDNA of peripheral blood has been unexploited in NKTCL patients.

Inclusion Criteria:

1. Diagnosis of NKTCL with typical morphology and immunophenotype, according to the 2008 World Health Organization classification of lymphomas;
2. stage III/IV disease; or relapsed or refractory disease after at least one line prior teratment;
3. age ≥ 18 years;
4. ECOG performance status 0-2;
5. at least one measurable lesion;
6. adequate hematological, hepatic, and renal functions;
7. life expectancy of more than 3 months.

Exclusion Criteria:

1. Previously untreated stage I/II disease;
2. with no adequate tumour tissue;
3. any coexisting medical problems of sufficient severity to prevent full compliance with the study protocol.

We plan to recurit 30 eligile patients who are diagnosed in our hospital.