3. KNOWN HBV INFECTION STATUS Patients with evidence of HBV infection by either: a. Patients who have had a positive HBsAg or anti-HBc test performed outside of MD Anderson within the last 3 months, and they have documented results in the electronic medical record at MD Anderson or, AND/OR b. Patients currently taking a medication (e.g., lamivudine, entecavir, tenofovir, adefovir, telbivudine, interferon, or other FDA-approved anti-hepatitis B drug) for the treatment of HBV infection.