In this episode, we discuss updated guidelines on the screening and management of hepatitis B virus (HBV) in patients about to start anticancer therapy. The guidelines come from an American Society of Clinical Oncology Provisional Clinical Opinion (PCO) published earlier this year. Jessica P. Hwang, MD, of MD Anderson Cancer Center, and Andrew Artz, MD, of City of Hope, are cochairs of the ASCO PCO. They joined host David H. Henry, MD, to discuss the guidelines. Epidemiology of HBV Data suggest chronic HBV infection affects 257 million people globally. In the United States, chronic HBV infection has a prevalence of less than 1%, but the prevalence of past HBV can be 5%-40% in high-risk populations. High-risk populations include people born in endemic areas (i.e., Africa, Asia, and South America), those with injection drug use, men who have sex with men, and people with household contacts who have HBV. In patients with cancer, the prevalence of past HBV infection is 5%-10%, with a 0.5% prevalence of chronic HBV. HBV and oncology: Who should be screened? The ASCO PCO recommends universal HBV screening in all patients planning or undergoing anticancer therapy. To screen, practitioners should order three tests before initiating anticancer therapy: hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc) total immunoglobulin (Ig) or IgG, and hepatitis B surface antibody (anti-Hbs). Interpretation of serology Chronic infection: HBsAg (+), anti-HBc (+), anti-HBs (-). Resolved past infection: HbsAg (-), anti-HBc (+), anti-HBs (+). Past infection, isolated core: HbsAg (-), anti-HBc (+), anti-HBs (-). Vaccine-induced immunity: HbsAg (-), anti-HBc (-), anti-HBs (+). Recommended treatment and/or monitoring Once a patient is infected, the HBV incorporates into the host genome and can live latently, so the patient is at risk of reactivation with immunosuppressive anticancer therapy (with chronic or past infection). Certain therapies pose a heightened risk of HBV reactivation, including anti-CD20 monoclonal antibodies and stem cell transplant. Patients receiving checkpoint blockade immunotherapy should be monitored closely for reactivation, though autoimmune hepatitis and high-dose steroids used in treating immune-related events could confound the reactivation of HBV. Further guidelines specific to checkpoint blockade immunotherapy are dichotomized and can be found in the ASCO PCO. In patients with chronic HBV infection receiving any systemic anticancer therapy, the ASCO PCO recommends antiviral prophylactic therapy during anticancer therapy and for a minimum of 12 months after anticancer therapy, with consultation of an HBV specialist. Entecavir, tenofovir disoproxil fumarate, and tenofovir alafenamide are well tolerated and have a low rate of viral resistance, making them favorable for patients who need to be treated. Implementing a screening program Recommend a multidisciplinary team approach, including physicians, pharmacists, and public health professionals. Utilize EHRs to incorporate alerts for screening and embedding screening into order sets. Ensure that positive test results are delivered to the appropriate medical team. Link patients into care for treatment and/or monitoring. Source and resources The ASCO PCO was published in the Journal of Clinical Oncology: https://bit.ly/3pClNPo. Additional resources are available on the ASCO website: https://bit.ly/35E0nt0. An infographic is also available: https://bit.ly/3pBuE3K. Show notes written by Sheila DeYoung, DO, a resident at Pennsylvania Hospital, Philadelphia. Disclosures Dr. Hwang disclosed relationships with Gilead Sciences, Merck Sharp & Dohme, and the Asian Health Foundation. Dr. Artz disclosed research funding from Miltenyi Biotec. Dr. Henry has no relevant disclosures. *  *  * For more MDedge Podcasts, go to mdedge.com/podcasts Email the show: podcasts@mdedge.com Interact with us on Twitter: @MDedgehemonc David Henry on Twitter: @davidhenrymd