Entecavir Prophylaxis for Hepatitis B Reactivation for CD20 Positive B-cell Lymphoma Patients With Resolved Hepatitis B (Negative Hepatitis B Surface Antigen, Positive Hepatitis B Core Antibody)

Inclusion Criteria: * Histopathologically confirmed CD20 positive B-cell lymphoma; * Plan to receive first-line anti-lymphoma therapy containing CD20 monoclonal antibodies; * Negative HBsAg, HBV-DNA lower than the detection limit and positive anti-HBC at baseline; * Total bilirubin less than 1.5X the upper limit of normal (ULN), AST and ALT less than 2.5X ULN; * ECOG PS: 0\~2; * Estimated survival time \>3 months. Exclusion Criteria: * Positive HBsAg or HBV-DNA higher than the detection limit at baseline; * Previous chemotherapy or radiotherapy for lymphoma; * Other primary liver diseases, such as chronic hepatitis C, hepatitis D, autoimmune hepatitis, Wilson' s disease or primary biliary cirrhosis; * Pregnant or lactating women; * History of immunodeficiency, including positive HIV, or other acquired congenital immunodeficiency disease, or history of organ transplantation.