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.