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To the Editor: The recent call by Robotin and colleagues for a national strategy to respond to the increasing incidence of hepatitis B and hepatocellular carcinoma (HCC) in Australia1 is timely. I would like to add the following comments.
First, a comprehensive Australian hepatitis B strategy should include prisoners and Indigenous Australians. Among Australian prisoners, hepatitis B carrier prevalence is 3%–5% — more than three times the national average — and prevalence of hepatitis C, which independently and synergistically increases the risk of severe liver disease, exceeds 30%.2 In addition, of 526 acute hepatitis B notifications in Australia in 2000–2002, 57 were in Indigenous Australians, a notification rate more than four times that in non-Indigenous Australians. Indigenous people are 12 times more likely to die of liver cancer than the general Australian population.3
Second, in New South Wales, the median age of diagnosis of HCC was found to vary significantly by country of birth;4 it was 5 years younger in the Asian-born group than the Australian-born group overall (64 v 69 years), and 9 years younger in those who were hepatitis B carriers (57 v 66 years) (P < 0.001 for both differences). Early onset of HCC among Asian-born Australians may be a result of hepatitis B infection in the perinatal and early childhood period. However, other factors that promote progression to HCC, such as diabetes, alcoholism, and inadequate health care access, are amenable to targeted public health interventions.
Third, hepatitis B e antigen (HbeAg) positivity is strongly associated with high hepatitis B virus DNA counts (≥ 100 000 copies/mL), which are in turn highly predictive of cirrhosis and HCC risk. It is thus counterintuitive that — as implied by Robotin et al — hepatitis B carriers who are positive for HbeAg are less likely to progress to cirrhosis and HCC than those who have undergone seroconversion and are positive for hepatitis B e antibody. In fact, HBeAg positivity is associated with increased risk of HCC and liver-related mortality.5,6
Finally, the omission of hepatitis B vaccine — the world’s first anticancer vaccine — from Robotin et al’s list of elements of a public health response to hepatitis B and liver cancer is unfortunate. Hepatitis B vaccination is essential to any credible medium- and long-term strategy to prevent hepatitis B infection and, by extension, HCC, both in Australia and globally.
School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW.
niyi.awofesoAThotmail.com
In reply: We agree with Awofeso that prisoners and Indigenous people have an increased risk of developing chronic hepatitis B. However, as no large-scale population-based studies of hepatitis B prevalence have been published in Australia, estimates of the risk vary widely.1 A national hepatitis B strategy may provide additional impetus for obtaining high-quality data. We also concur that modifiable behavioural factors may play a role in the age of hepatocellular carcinoma diagnosis, but differences in clinical course between Asian and white Australians,2 and the specific viral genotypes prevalent in Asia,3 are likely to be more important.
Although white populations who undergo hepatitis B e antigen (HbeAg) seroconversion and develop hepatitis B e antibodies have a good prognosis, this is not so for Asian populations,2 or for other populations who are mostly infected in childhood, such as Indigenous Australians and Māori in New Zealand. The median age of HBeAg seroconversion in Asian patients with chronic hepatitis B is 34.5 years,4 while the median age at diagnosis of hepatocellular carcinoma of Asian patients quoted by Awofeso is 57 years, by which age most would have seroconverted.
Australia has been successful in primary prevention of hepatitis B through vaccination (albeit less so in migrants, some Indigenous communities and catch-up vaccination), and hence the omission of vaccination from our “wish list” for a public health response. However, Australia has been less successful in secondary and tertiary prevention. We hope that a national strategy would be a catalyst for these interventions to be given the priority they deserve.
1 Cancer Council New South Wales, Sydney, NSW.
2 University of Sydney, Sydney, NSW.
3 Westmead Hospital, Sydney, NSW.
monicarATnswcc.org.au
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©The Medical Journal of Australia 2008 www.mja.com.au PRINT ISSN: 0025-729X ONLINE ISSN: 1326-5377