A Clinical Trial of Decitabine in Relapse and Refractory Diffuse Large B Cell Lymphoma

Inclusion Criteria: * age:14-65 years;ECOG rate≤2;expected survival≥3 months * patients with Diffuse Large B cell lymphoma diagnoesd by histopathology detection; * patients ever received RCHOP or CHOP chemotherapy but did not receive DHAP * patients never received radiotherapy * patients with no chemotherapy contraindications:hemoglobin ≥ 90g/L,absoluate neutrophil count ≥1.5x109/L,blood platelet ≥100x109/L,ALT and AST ≤ 2-fold upper normal limit,serum bilirubin ≤1.5-fold upper normal limit,serum creatinine ≤1.5-fold upper normal limit,serum albumin ≥ 30g/L,normal serofibrinogen; * at least one measurable nidus; * no other severe diseases conflict with this project,cardiopulmonary function is basically normal * the urine or blood pregnancy test of women in childbearing age must be negative in 7 days before follow-up visit; * applicable for follow-up visit; * no other antitumor adjoint therapy(including antitumor Chinese medicine,immunotherapy and biotherapy),but double phosphate anti-bone transfer therapy and other symptomatic treatment are acceptable; * understanding this study and assigning informed consent. Exclusion Criteria: * rejecting providing blood preparation; * allergic to drug in this study and with metabolic block; * rejecting adopting reliable contraceptive method in pregnancy or lactation period; * uncontrolled internal medicine disease(including uncontrolled diabetes,severe incompetence cardiac,lung,liver and pancreas）； * with severe infection; * with primary or secondary central nervous system tumor invasion; * with immunotherapy or radiotherapy contraindication; * ever suffered with malignant tumor; * having peripheral nervous system disorder or dysphrenia; * with no legal capacity,medical or ethical reasons affecting research proceeding; * participating other clinical trials simultaneously; * adopting other anti-tumor medicine excluding this research; * the researchers considering it inappropriate to participate in the study.