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)

All patients enrolled in the study will accept entecavir prophylaxis that initiates within 1 week before the first course of CD20 monoclonal antibody therapy, and continues until 6 months after completing CD20 monoclonal antibody therapy.