 Association between HBV reactivation and serological breakthrough i.e., re-appearance of HBsAg during follow-up Association between HBV reactivation and levels of anti-HBc antibodies during follow-up Association between HBV reactivation and HLA germline polymorphism HLA-DPA1, HLA-DPB1, HLA-DQA1, HLA-DQB1, HLA-DRB1 IL28B genotype of the patients Progression-free survival and overall survival for patients who receive rituximab-CHOP chemotherapy. 