Why Hepatitis B Matters During Cancer Treatment

Before starting chemotherapy, immunotherapy or another cancer treatment, many patients are asked to take a blood test for hepatitis B. During Liver Cancer Awareness Month in October, here is what to know about why that test matters, based on guidance from the American Society of Clinical Oncology (ASCO), published in July 2020, and the Centers for Disease Control and Prevention (CDC), published in March 2023.

Hepatitis B is a virus that infects the liver. Many people who have it do not know. The CDC estimates that 580,000 to 2.4 million people in the United States are living with hepatitis B infection, and that about two-thirds of them might be unaware they are infected.

Why Hepatitis B Matters During Cancer Treatment

In someone who has hepatitis B now, or who had it in the past, the virus can stay quiet in the body for years. Some cancer treatments weaken the immune system, which can allow the virus to become active again. This is called hepatitis B reactivation, and it can cause liver inflammation and liver damage. The CDC says people who have weakened immune systems should be considered at risk for reactivation.

Knowing your hepatitis B status before treatment starts gives your care team the chance to prevent reactivation or catch it early.

Who Should Get Tested for Hepatitis B

• People with cancer: ASCO recommends universal hepatitis B screening for patients with cancer who expect to receive systemic anticancer therapy, meaning treatment that travels through the body, such as chemotherapy, targeted therapy or immunotherapy.
• All adults: Separately, the CDC recommends that all adults ages 18 and older be screened for hepatitis B at least once in their lifetime. The CDC also notes that screening might be recommended for people starting cytotoxic or immunosuppressive therapy.

Which Hepatitis B Tests Are Used

Both ASCO and the CDC recommend three blood tests, often called a “triple panel,” to assess hepatitis B status. The hepatitis B surface antigen (HBsAg) test can indicate a current infection, while the total hepatitis B core antibody (anti-HBc) test indicates a past or current infection. The hepatitis B surface antibody (anti-HBs) test shows whether a person has protection from vaccination or a past infection. According to ASCO, a negative anti-HBs result may indicate a higher risk of hepatitis B reactivation in people with a past infection.Both ASCO and the CDC point to the same three blood tests, often called a "triple panel":

What Happens if Your Test Is Positive

A positive hepatitis B test does not usually mean you cannot get cancer treatment. It means your care team will plan for it. According to ASCO's guidance:

• Antiviral medicine: Most people with a current infection (HBsAg-positive) should take an antiviral medicine to prevent reactivation. Some people with a past infection (HBsAg-negative and anti-HBc-positive) should also take one if their cancer treatment carries a significant risk of reactivation. Preferred medicines are entecavir, tenofovir disoproxil fumarate or tenofovir alafenamide.
• How long: Antiviral medicine is usually taken during cancer treatment and for up to 12 months afterward.
• Higher-risk treatments: ASCO names anti-CD20 antibodies, a type of treatment used for some lymphomas and leukemias, and stem cell transplants as treatments that may raise the risk of reactivation. Hormone therapy alone is not known to substantially raise the risk.
• Monitoring: Your care team may check blood levels of the virus (HBV DNA) and liver tests during and after treatment. People with a past infection who are not on high-risk treatment may be monitored closely and started on antiviral medicine at the first sign of reactivation.
• A liver specialist: ASCO recommends involving a clinician experienced in treating hepatitis B.

What It Means for You

A hepatitis B test is a simple blood draw that can protect your liver during cancer treatment. If you have never been tested, or are not sure, it is reasonable to ask before treatment begins. If you test positive, ask your team to explain your plan, including how long to take antiviral medicine and why it is important not to stop it on your own. Hepatitis infections often go unrecognized in people with cancer, as CURE has reported.

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