HBV remains major contributor to primary liver cancer globally
medwireNews: Hepatitis B virus (HBV) infection is the leading cause of incident primary liver cancer and associated mortality worldwide, according to research published in JAMA Oncology.
And a study from northern China, published in the International Journal of Infectious Diseases, suggests the impact of HBV could even be underestimated in some regions.
Christina Fitzmaurice (University of Washington, Seattle, USA) and fellow members of the Liver Cancer Collaboration of the Global Burden of Disease study used data from death and cancer registries from 195 countries and found that there were 854,000 incident cases of liver cancer and 810,000 deaths on a global scale in 2015.
HBV infection was the leading cause of incident liver cancer, accounting for 32% of cases, followed by alcohol (29%), hepatitis C virus (HCV; 23%), and other etiologies including liver flukes, nonalcoholic steatohepatitis, and aflatoxins (16%).
The same pattern was seen for liver cancer-associated mortality, with HBV underlying 33% of deaths, and alcohol (30%), HCV (21%), and other causes (16%) accounting for the remaining deaths.
There were marked differences across regions and countries in terms of the contribution of HBV infection to liver cancer deaths. For instance, only 6% of deaths in Southern Latin America could be attributed to HBV compared with 45% in Western sub-Saharan Africa and Andean Latin America. And by country, the proportion of HBV-related liver cancer deaths ranged from 4% in Mexico to 60% in The Gambia.
Similar variations were also observed for the other etiologic factors included in the study.
The researchers also compared global incident liver cancer cases between 1995 and 2015, finding a 75% increase over time, primarily attributable to changing population age structures and size. However, they estimate that if these factors had remained unchanged, incident cases due to HBV would have declined by 35%, which the team says highlights that “primary liver cancer prevention through HBV vaccination is starting to show successes.”
In conclusion, Fitzmaurice et al write that their findings demonstrate that “most cases of liver cancer can be prevented through vaccination, antiviral treatment, safe blood transfusion and injection practices, as well as interventions to reduce excessive alcohol use.”
The second study addressed a similar issue but focused on the impact of just the viral etiologic factors on primary liver cancer in the northern regions of China.
The team from the Chinese Academy of Medical Sciences and Peking Union Medical College in Beijing identified 2172 patients who received a histologically confirmed diagnosis of primary liver cancer at their institution between 2003 and 2014. The majority (83.9%) had hepatocellular carcinoma (HCC).
Most (86.0%) of the 1823 HCC patients tested positive for serologic markers signifying HBV infection, specifically hepatitis B surface antigen (HBsAg) positivity or negativity alongside the presence of antibodies against HBV core antigen (anti-HBc). Just 2.5% of cases had serologic evidence of infection with HCV alone, while 6.7% showed evidence of co-infection and 4.8% tested negative for serologic markers of HBV or HCV.
A “substantial proportion” of the patients with HCC were anti-HBc-positive in the absence of HBsAg, at 18.2%, and 70.3% of these cases had detectable serum HBV DNA, which is indicative of active HBV replication and occult infection status, say Chunfeng Qu and co-researchers.
They point out that altogether HBV infection was the underlying etiologic factor for at least 85–90% of HCC cases, suggesting that “the contribution of HBV infection to HCC in China has previously been underestimated, most probably due to the unrecognized status of occult HBV infection among HBsAg-negative HCC cases.”
Qu et al say that since the initiation of universal HBV vaccination in 2002, HBsAg seroprevalence has dropped to less than 1% in children younger than 5 years.
But as research has shown that most Chinese adults were not vaccinated against HBV in infancy, they conclude that “the effect of antiviral therapy in decreasing the incidence of liver cancer in the general population, particularly HCC, should be evaluated carefully.”
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