Before chemotherapy, immunosuppression, or biologics: do not miss hepatitis B reactivation risk

Why this needs to be discussed early

Some people had hepatitis B in the past and are now HBsAg negative, have no symptoms, or only know that anti-HBc is positive. Others are HBsAg positive but have stable liver tests. After chemotherapy, immune-suppressing treatment, biologics, transplant-related therapy, or long-term high-dose steroids, HBV can replicate again and cause hepatitis flares that may interrupt cancer, rheumatology, kidney, blood disease, or transplant treatment.

This is called HBV reactivation. It is not a new infection from someone else; it is previous or current HBV becoming active under immune pressure. Because many people have no symptoms beforehand, the practical step is to screen and plan before high-risk therapy starts.

Treatments that should prompt HBV screening questions

Before systemic cancer therapy, chemotherapy, anti-CD20 medicines, stem cell transplant, organ transplant immune suppression, CAR-T or other cell therapy, long-term or high-dose steroids, JAK inhibitors, TNF inhibitors, B-cell or T-cell targeted therapy, or biologics for rheumatologic or inflammatory bowel disease, ask: Do I need HBsAg, anti-HBc, and anti-HBs testing or a complete HBV screen?

ASCO recommends HBsAg, anti-HBc, and anti-HBs testing for people preparing for systemic anticancer therapy. CDC screening recommendations also include people receiving or needing cytotoxic, immunosuppressive, or immunomodulatory therapy. The final plan may need oncology, rheumatology, hematology, nephrology, transplant, and liver or infectious disease teams.

What information to bring

Before treatment, organize HBsAg, anti-HBs, total or IgG anti-HBc, sometimes anti-HBc IgM, HBV DNA, ALT/AST, bilirubin, albumin, INR, platelets, liver ultrasound or fibrosis assessment, and any past use of entecavir, tenofovir, or other antivirals.

If you only remember being told that you had hepatitis B, were a carrier as a child, or had positive core antibody on a checkup, do not treat that as a minor detail. Bring old reports or photos, and tell the clinician the treatment name, expected start date, expected duration, and whether multiple immune-suppressing medicines will be combined.

Possible management plans

People who are HBsAg positive are often assessed for preventive antiviral therapy before many high-risk treatments. People who are HBsAg negative but anti-HBc positive may also need preventive antivirals for some high-risk regimens, or close monitoring for lower-risk regimens. AASLD guidance emphasizes that reactivation risk depends on HBV serology and medication risk, not only whether ALT is normal that day.

The antiviral choice, when to start, how long to continue, and how long to monitor after stopping should be decided by clinicians. Do not buy antivirals on your own to rush treatment, and do not assume there is no risk because HBV DNA was undetectable once.

Eight questions to ask

1. Have I been tested for HBsAg, anti-HBc, and anti-HBs before this treatment?
2. If HBsAg is positive, should antivirals start before treatment?
3. If HBsAg is negative but anti-HBc is positive, is my regimen high, moderate, or low risk?
4. Do I need HBV DNA, ALT/AST, and baseline liver assessment?
5. How long before treatment should antivirals start, and how long after treatment should they continue?
6. If monitoring is chosen instead of preventive therapy, how often should HBV DNA and ALT be checked?
7. If ALT rises or HBV DNA becomes positive during treatment, which team should I contact and what is the process?
8. Do family members or partners need screening or hepatitis B vaccination?

Action checklist

Put HBV screening on the to-do list before chemotherapy, immunosuppression, or biologics. Save all old hepatitis B reports. Send the treatment regimen name to a liver or infectious disease clinician. Confirm whether preventive antivirals or scheduled monitoring are needed. After treatment starts, follow the monitoring plan and do not stop antivirals on your own or miss post-treatment follow-up.