Scientists Discover Cancer Marker Associated with Hepatitis B
In a groundbreaking development, researchers from National Taiwan University Hospital (NTUH) have found that the serum hepatitis B surface antigen (HBsAg) plays a crucial role in both determining treatment for people with chronic hepatitis B (CHB) and guiding cancer surveillance strategies.
Role in Treatment Determination:
The persistent presence of HBsAg confirms chronic HBV infection, identifying patients who require evaluation for antiviral therapy. Those who are HBsAg positive with elevated HBV DNA and liver inflammation (high ALT) are candidates for treatment, typically with first-line oral antivirals such as entecavir or tenofovir. The presence of serum HBsAg guides clinicians when to start therapy to suppress viral replication and prevent liver damage.
Quantitative HBsAg levels can be used to monitor response to therapy. Decline or loss of HBsAg signals successful viral suppression and possibly the cessation of treatment. In pregnant women, HBsAg positivity combined with high viral load (HBV DNA ≥200,000 IU/mL) prompts antiviral therapy during the third trimester to reduce perinatal transmission risk.
Role in Cancer Surveillance:
Persistent HBsAg positivity in chronic HBV reflects ongoing viral activity, which is associated with increased risk of liver cancer. Therefore, regular HBsAg testing helps in identifying patients needing hepatocellular carcinoma surveillance. Loss of HBsAg can indicate lower HCC risk, allowing adjustment of surveillance strategies; in contrast, continued positivity may necessitate more rigorous monitoring with imaging and alpha-fetoprotein tests.
The findings of the first study, published in the June edition of Gut, reveal that non-cirrhotic inactive chronic hepatitis B carriers with HBsAg levels below 100 IU/mL had an annual liver cancer incidence of only 0.08 percent. About one-third of inactive chronic hepatitis B carriers have low HBsAg levels. This could mean that approximately one-third of people in the low-risk group may not require frequent examinations, freeing up resources in areas where they are limited.
The second study, published in March in the medical journal Hepatology, found that chronic hepatitis B carriers in the immune-tolerant phase with HBsAg greater than 10,000 IU/mL were associated with delayed development of liver cancer. This suggests that for those with HBsAg above 100 IU/mL, new antiviral treatments could be considered to suppress the antigen and reduce the risk of liver cancer.
The research, based on follow-up periods of up to 20 or more years, has significant implications for precision medicine and optimizing liver cancer surveillance strategies. The results of the second study were validated in a large Japanese cohort study, and the antigen could be used as a biomarker to identify those who are truly in the low-risk, immune-tolerant phase and avoid unnecessary treatment.
The research analysed long-term follow-up data from cohort studies led by NTUH vice superintendent Kao Jia-horng and Academia Sinica academician and former vice president Chen Chien-jen. The findings highlight the importance of HBsAg as a key indicator in managing chronic hepatitis B and reducing liver cancer deaths, which was the second-highest number of cancer deaths in Taiwan last year.
