Hepatocellular carcinoma in young, mentally retarded HBsAg carriers without cirrhosis

Hepatitis B virus and hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100-fold increased relative risk of developing the tumour. Several mechanisms of HBV-induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV-associated HCC.

Hepatitis B virus and hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100-fold increased relative risk of developing the tumour. Several mechanisms of HBV-induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV-associated HCC.

Hepatitis B virus infection and primary hepatocellular carcinoma

For many years, epidemiological studies have demonstrated a strong link between chronic hepatitis B virus (HBV) infection and the development of primary hepatocellular carcinoma (PHC). Other hepatocarcinogens such as hepatitis C virus and aflatoxin also contribute to hepatocarcinogenesis either in conjunction with HBV infection or alone. Cellular and molecular biological studies are providing explanations for the HBV-PHC relationship, and models are now being formulated to further test the relative importance of various factors such as viral DNA integration, activation of oncogenes, genetic instability, loss of tumor suppressor genes, and trans-activating properties of HBV to the pathogenesis of PHC. Further research will probably define more than a single mechanism whereby chronic HBV infection results in PHC.

Hepatitis B virus related hepatocellular carcinoma in the non-cirrhotic liver

To complement investigations of hepatitis B virus infection in hepatocellular carcinoma associated with cirrhosis, we studied hepatitis B virus infection in 137 hepatoma patients without cirrhosis. Ninety-five were from the U.K. (where the prevalence of hepatitis B virus markers is very low) and 42 were from overseas. Of these 137 patients, seven (5%) were hepatitis B surface antigen seropositive. None of the hepatitis B surface antigen positive patients had any recognisable risk factors other than birth in an area of high hepatitis B virus prevalence in four of the patients. Of the 95 U.K. patients three (3%) were hepatitis B surface antigen positive as compared to a carriage rate of less than 0.1% in the normal population. The frequency of antibodies to hepatitis B surface and core antigens alone (both 7.5%) was also higher than that seen in the normal U.K. population (2.4%). Histological examination of the non-tumorous liver showed fine fibrous septa in three patients, more extensive subcapsular scars in one, chronic persistent hepatitis in two and non-specific inflammation in one. On immunohistochemical examination five patients had hepatitis B surface antigen (but not core antigen) detectable in the non-tumorous liver tissue. Hepatitis B virus infection appears to be a small, but significant, risk factor for the development of hepatoma in the non-cirrhotic group.

Viral hepatitis

Recent research has led to a greater understanding of the mechanisms and management of the various forms of viral hepatitis. The clinician can rapidly arrive at a precise diagnosis using serologic markers to complement epidemiologic data. In addition, effective immunoprophylaxis is possible; thus, disease spread can be minimized.

Serum alpha fetoprotein in 714 mentally retarded carriers of hepatitis B surface antigen

Sera from 714 mentally retarded carriers of hepatitis B surface antigen were screened for alpha fetoprotein (AFP) by monoclonal radioimmunoassay. Serum AFP levels were less than 20 mcg/L in 708 (99.2%) carriers. One 29-year-old carrier with normal liver function had serum AFP level of 1500 mcg/L, which increased to 12,500 mcg/L after 72 days. She died of multifocal hepatocellular carcinoma (HCC) with cirrhosis. Five other carriers with serum AFP levels between 20 and 165 mcg/L are alive without clinical HCC. No correlation was found between serum AFP level and race, age, sex, Down's syndrome, serum alanine aminotransferase level, and hepatitis B e antigen positivity. Single cross-sectional serum AFP screening by itself is not sufficient for early diagnosis of HCC.

Viral hepatitis

Recent research has led to a greater understanding of the mechanisms and management of the various forms of viral hepatitis. The clinician can rapidly arrive at a precise diagnosis using serologic markers to complement epidemiologic data. In addition, effective immunoprophylaxis is possible; thus disease spread can be minimized.

Aflatoxin content of foods served to a population with a high incidence of hepatocellular carcinoma

During three seasons, 36 samples of foods served to mentally retarded clients with a high incidence of hepatocellular carcinoma were analyzed for aflatoxin. Aflatoxin was not detected (less than 5 ppb) by thin-layer liquid chromatography in 35 food samples containing peanuts, corn, wheat or milk. One peanut butter sample contained 20 ppb aflatoxin. Aflatoxin content of these foods was at or below the level permitted by the Food and Drug Administration. Aflatoxin is probably not responsible for liver disease in this population.

Aetiological factors in hepatocellular cancer

The major risk factors for HCC are outlined in Table 2. Each factor may contribute to the multistep process of hepatocarcinogenesis. Hepatitis B virus and aflatoxins are the principal aetiological candidates and may be considered as initiators of the malignant state (see Figure 1). The majority of HCC arises via the cirrhotic pathway; the associated changes in the hormonal milieu may alter the handling of environmental carcinogens and the rounds of cell proliferation may increase sensitivity to sub-threshold doses of carcinogens. Exogenous androgens and oestrogens may operate through a similar mechanism to promote clonal expansion of preneoplastic cells. The importance of identifying the major aetiological factors lies in the possibility of prevention. The prognosis of HCC is dismal and it represents a major scourge in developing Third World countries. It is encouraging to think that the majority of cases could be prevented by the widespread use of hepatitis B vaccines and the development of intervention programmes against aflatoxin contamination of foodstuffs.