Hepatitis B virus (HBV) and hepatocellular carcinoma. HBV DNA status and its implications

Improved timely birth dose coverage of hepatitis B vaccine narrows the socio-economic inequality in western China in 2011-2016

OBJECTIVE

To compare timely birth dose (TBD) coverage of hepatitis B vaccine and socio-economic inequality distribution of TBD coverage between 2011 and 2016 in rural areas of western China.

METHODS

In western China, using multi-stage probability proportion to size sampling, 2633 and 1929 children aged 0-35 months with an immunization card were selected from 14 rural counties in 2011 and 2016, respectively. Socio-economic characteristics were obtained from face-to-face questionnaire survey and copies of vaccination certificates. We performed multivariate logistic regression models to identify the determinants of TBD coverage of hepatitis B vaccine. We grouped TBD coverage by wealth quintiles, calculated inequality using the difference base on coverage in richest (quintile 5) and poorest (quintile 1) household wealth quintiles.

FINDINGS

From 2011 to 2016, the overall TBD coverage of hepatitis B vaccine among children aged 0-35 months in rural areas of western China increased from 52.8% (95% confidence interval, CI: 42.4-62.8) to 80.2% (95% CI: 69.5-87.8). The absolute difference in TBD coverage between richest and poorest quintiles was 20.6 (95%CI: 9.4-31.8) and 15.8 (95%CI: 1.4-30.2) in 2011 and 2016, respectively.

CONCLUSION

The socioeconomic inequality in TBD coverage decreased over the study period, but such inequality still existed in 2016. To improve inequality in TBD, the government should pay more attention to the disadvantaged groups, especially the children who were delivered at home, or whose caregivers were ethnic minority or who have a lower level of education.

Immune response to hepatitis B vaccine in patients with chronic hepatitis C infection: A systematic review and meta-analysis

Hepatitis B virus and hepatitis C virus (HCV) co-infection can add to the severity of hepatitis and the risks of liver cirrhosis and hepatocellular carcinoma. Whether chronic HCV infection decreases antibody response to hepatitis B vaccination is still controversial. We evaluate the influence of HCV infection on antibody response to hepatitis B vaccination by a systematic review of published works with a meta-analysis of clinical trials. The random-effects model of DerSimonian and Laird with heterogeneity and sensitivity analyses were used in this study. The end-point of interest was the rate of patients showing seroconversion of antibody responses at completion of hepatitis B vaccination schedule among patients with chronic HCV infection versus healthy controls. We identified 11 studies involving 704 patients with HCV and 812 controls. Our results show a significant decrease in antibody seroconversion rates among patients with HCV versus healthy controls (pooled odds ratio = 0.17 [95% confidence interval, 0.11-0.28]). The P-value was 0.21 for our test of study heterogeneity. Stratified analysis in subgroups of interest and sensitivity analysis did not meaningfully change our results. Our meta-analysis showed patients with hepatitis C infection have a statistically significant lower rate of seroconversion in comparison to healthy controls, both in cirrhotic and non-cirrhotic patients. Chronic HCV infection can decrease the immune response to a standard schedule of hepatitis B vaccination. Further studies are needed to investigate the optimum vaccination schedule for patients with chronic HCV infection.

Robust Antibody and Cytokine Response to Hepatitis B Vaccine Among Not-in-Treatment Patients With Chronic Hepatitis C: An Open-Label Control Study in China

Background

Hepatitis B vaccine is an effective measure to prevent hepatitis B virus infection. Whether chronic hepatitis C virus (HCV) infection decreases humoral and cell-mediated immunity responses to hepatitis B vaccination is still controversial.

Methods

Patients with chronic HCV infection who were not in treatment and healthy controls, matched at a 1:2 ratio for community, sex, and age (within 5 years), were identified from a community-based screening. All participants received 3 doses of hepatitis B vaccine. Antibody to hepatitis B surface antigen was tested 1 month after the third vaccine dose and was compared between 2 groups. Spot-forming cells (SFCs) of interferon γ and interleukin 2, 4, 5, and 6 were counted by means of enzyme-linked immunospot, and SFC counts were compared between the 2 groups.

Results

The rates of nonresponse and low, normal, and high response were 3.80%, 10.13%, 45.57%, and 40.50% respectively, in the HCV group, and the corresponding rates in the healthy control group were 1.26%, 10.13%, 39.24%, and 49.37% (all P > .05). There were no significant differences in SFC counts between the 2 groups for interferon γ or interleukin 2, 4, or 5 (all P > .05).

Conclusions

This study provided preliminary evidence of the good immunogenicity and safety of hepatitis B vaccination among patients in China with chronic hepatitis C who are not in treatment.

Clinical Trials Registration

NCT 02898922.

Risk of Onset of Hematological Malignancies in Patients Infected with the Hepatitis B Virus: Results from a Large-Scale Retrospective Cohort Study in China

The hepatitis B virus (HBV) is a major global issue, because an increased risk of hepatocellular carcinoma among patients infected with HBV is well established. Recently, it has been suggested that HBV is associated with other human cancers. However, the association between HBV and the risk of onset of hematological malignancies remains controversial. The aim of this large-scale retrospective cohort study was to evaluate the association between HBV infection and hematological malignancies. A retrospective analysis of 86,115 newly admitted patients at Shanghai Ruijin Hospital was performed. A cohort of patients previously exposed to HBV (n = 1,874) and a cohort of individuals without a positive test for anti-hepatitis B core antigen (anti-HBc; n = 45,118) were compared to assess the risk of hematological malignancies. Anti-HBc was positive in 61.2% cases and 54.3% controls (p = 0.0001). The risk of B cell non-Hodgkin's lymphoma, acute lymphoblastic leukemia, and multiple myeloma was higher in the HBV-infected cohort than in the non-HBV-infected cohort. In conclusion, patients infected with HBV have a substantially increased risk of hematological malignancies.

Glycosylation and liver cancer

Liver cancer is the fifth most common cancer, but the second leading cause of cancer death, in the world, with more than 700,000 fatalities annually. The major etiology of liver cancer is infection with an hepatotropic virus such as hepatitis B virus or hepatitis C virus infection. While chronic viral infection remains the main cause of liver disease and risk of hepatocellular carcinoma (HCC), rates of nonviral-associated HCC are occurring at an alarmingly increasing rate. Like many cancers, survival rates are closely associated with time of detection. If HCC is caught early, survival rates can be as high as 50%. Regrettably, most cases of HCC are caught late where survival rates can be as low as 2-7%. Thus, there has been great interest in discovering serum biomarkers that could be used to identify those with HCC. To this end, many groups have examined the N-linked glycans to identify changes that occur with HCC. As the liver secretes the vast majority of proteins into the serum, this has often been a starting point for study. In serum, alterations in core fucosylation, outer-arm fucosylation, increased sialylation, and glycan branching have been observed in patients with HCC. Similar findings have been found directly in HCC tissue suggesting that these glycan changes may play a role in tumor formation and development.

Proinflammatory homeobox gene, ISX, regulates tumor growth and survival in hepatocellular carcinoma

Chronic inflammation drives initiation of hepatocellular carcinoma (HCC), but the underlying mechanisms linking inflammation and tumor formation remain obscure. In this study, we compared the expression of interleukin (IL)-6 and cyclin D1 (CCND1) with the IL-6-induced homeobox gene ISX (intestine-specific homeobox) in 119 paired specimens of HCCs and adjacent normal tissues and also in paired specimens from 11 patients with non-HCCs. In pathologic analysis, ISX exhibited a tumor-specific expression pattern and a high correlation to patient survival time, tumor size, tumor number, and progression stage. Enforced expression of ISX accelerated cell proliferation and tumorigenic activity in hepatoma cells through CCND1 induction. In contrast, short hairpin RNA-mediated attenuation of ISX in hepatoma cells decreased cell proliferation and malignant transformation in vitro and in vivo. A high positive correlation existed in human hepatoma tumors between ISX and CCND1 expression. Together, our results highlight ISX as an important regulator in hepatoma progression with significant potential as a prognostic and therapeutic target in HCCs.

Influence of serum HBV DNA load on recurrence of hepatocellular carcinoma after treatment with percutaneous radiofrequency ablation

BACKGROUND

High serum load of hepatitis B virus (HBV) deoxyribonucleic acid (DNA) is a strong risk factor of hepatocellular carcinoma (HCC) development, independent of hepatitis B e antigen, serum alanine aminotransferase level, and liver cirrhosis. We evaluated whether serum HBV DNA load is associated with the risk of recurrence of HBV-related HCC treated with radiofrequency ablation (RFA).

METHODS

The study population was 69 consecutive patients with HBV-related HCC treated locally completely with RFA between January 2000 and September 2007. The risk factors for HCC recurrence were analyzed based on laboratory data, including serum HBV DNA load, together with tumor size and number using univariate and multivariate proportional hazard regression analyses.

RESULTS

HCC recurrence was observed in 42 of 69 patients during the median observation period of 1.5 years. Cumulative recurrence rates at 1, 3, and 5 years were 26.5, 57.8, and 74.3%, respectively. In univariate analysis, albumin (<3.5 g/dl), platelet count (<150 × 10(3)/mm(3)), prothrombin activity (PT) (<70%), Child-Pugh class B, serum HBV DNA load (>4.0 log10 copies/ml), and tumor number (>3) were associated with the recurrence at p ≤ 0.15. Multivariate Cox regression analysis with stepwise variable selection showed that the tumor number (risk ratio, 4.63; 95% CI, 1.50-14.25, P = 0.0076), low PT (3.39, 1.52-5.78, P = 0.0029), and high HBV DNA load (2.67, 1.16-6.14, P = 0.021) were independent risk factors for HCC recurrence.

CONCLUSION

Serum HBV DNA load is associated with the risk of recurrence of HBV-related HCC after RFA.

Identification and development of fucosylated glycoproteins as biomarkers of primary hepatocellular carcinoma

Changes in N-linked glycosylation are known to occur during the development of cancer. For example, we have previously reported changes in N-linked glycosylation that occur with the development of hepatocellular carcinoma (HCC) and, through the use of glycoproteomics, identified many of those proteins containing altered glycan structures. To advance these studies and further explore the glycoproteome, we performed N-linked glycan analysis from serum samples depleted of the major acute phase proteins, followed by targeted lectin extraction of those proteins containing changes in glycosylation. Using this method, changes in glycosylation, specifically increased amounts of core and outer arm fucosylation, were observed in the depleted samples. The identities of those proteins containing core and outer arm fucose were identified in the serum of patients with HCC. The usefulness of some of these proteins in the diagnosis of HCC was determined through the analysis of over 300 patient samples using a high-throughput plate based approach. Greatest performance was achieved with fucosylated hemopexin, which had an AUROC of 0.9515 with an optimal sensitivity of 92% and a specificity of 92%.

Association between hepatitis B virus and pancreatic cancer

PURPOSE

Hepatitis B virus (HBV) and hepatitis C virus (HCV) are considered to be hepatotropic and are a major cause of hepatocellular carcinoma. However, little is known about the role of HBV and HCV infection in other malignancies. This study aimed to determine whether HBV and HCV infections increase the risk for pancreatic cancer development.

PATIENTS AND METHODS

At The University of Texas M. D. Anderson Cancer Center, Houston, TX, we recruited 476 patients with pathologically confirmed adenocarcinoma of the pancreas and 879 age-, sex-, and race-matched healthy controls. Blood samples were tested for the presence of HCV antibodies (anti-HCV), HBV surface antigen (HBsAg), antibodies against HBV core antigen (anti-HBc), and antibodies against HBsAg (anti-HBs). The positive samples were retested by two confirmatory tests. An unconditional multivariable logistic regression analysis was used to estimate adjusted odds ratios (AORs).

RESULTS

Anti-HCV was positive in seven cases (1.5%) and nine controls (1%). Anti-HBc was positive in 36 cases (7.6%) and 28 controls (3.2%). The estimated AORs and 95% CIs were as follows: anti-HCV-positive, 0.9 (95% CI, 0.3 to 2.8), anti-HBc-positive, 2.5 (95% CI, 1.5 to 4.2), anti-HBc-positive/anti-HBs-positive, 2.3 (95% CI, 1.2 to 4.2), and anti-HBc-positive/anti-HBs-negative, 4 (95% CI, 1.4 to 11.1). Risk modification by past exposure to HBV was observed among diabetics (AOR, 7.1; 95% CI, 1.7 to 28.7).

CONCLUSION

Past exposure to HBV may be associated with pancreatic cancer development. Should such findings be confirmed by other studies, it may offer important insights into the etiology of pancreatic cancer and may suggest the need to consider prevention of HBV reactivation among patients with HBV-related pancreatic cancer during chemotherapy.

Outer arm fucosylation of N-glycans increases in sera of hepatocellular carcinoma patients

Serum glycans are promising markers for early-stage cancer detection, but the research remains challenging because low concentrations of serum glycoproteins are secreted from early-stage tumors. We have established an N-glycan profiling method using liquid chromatography electrospray ionization-mass spectrometry with high sensitive derivative, trimethyl(4-aminophenyl)ammonium chloride (TMAPA). The mass sensitivity of TMAPA-labeled oligosaccharides was enhanced more than 50 times compared with 2-aminopyridine (PA) labeled oligosaccharides, and the analytical period was significantly shortened compared with traditional HPLC 2D-mapping. Using this method, we found about 28 major N-linked oligosaccharides in human sera, and we investigated their alterations in patients who developed hepatocellular carcinoma (HCC). We found that outer arm fucosylation (attached GlcNAc via an alpha 1-3/4 linkage) in highly branched oligosaccharides increased significantly in sera of HCC patients. Normalizing the level of outer arm fucosylation by taking into account platelet concentration allowed us to distinguish more clearly between HCC and LC patients.

Proteomic analysis of serum associated fucosylated glycoproteins in the development of primary hepatocellular carcinoma

Changes in N-linked glycosylation are known to occur during the development of cancer. For example, increased branching of oligosaccharides has been associated with metastasis and has been correlated to tumor progression in human cancers of the breast, colon and melanomas. Increases in core fucosylation have also been associated with the development of hepatocellular carcinoma (HCC). Chronic infection with the hepatitis B virus is associated with more than 55% of all cases of hepatocellular carcinoma. We show here that increased levels of core fucosylation can be observed via glycan analysis of total serum and are associated with the development of HCC. In a blinded study, the serum glycoproteins derived from people diagnosed with HBV induced liver cancer were found to possess a dramatically higher level of fucosylation. This change occurs on both immunoglobulin molecules and on other serum glycoproteins. Targeted glycoproteomic analysis was used to identify those glycoproteins that are hyperfucosylated in cancer. In total, 19 proteins were found to be hyperfucosylated in cancer. The potential of these proteins as biomarkers of cancer is discussed.

Dominant mutations of hepatitis B virus variants in hepatoma accumulate in B-cell and T-cell epitopes of the HBx antigen

Hepatitis B virus (HBV) X gene, encoding a pleotropic transactivator of HBx protein, has been associated with the development of hepatocellular carcinoma (HCC). Molecular information on liver-derived HBV variants isolated from HCC among Taiwanese population was studied. Amplification of the HBV X genes of 20 HCC patients in high stringency with HBV specific primers was observed. The resulting amplified HBV X genes were purified and individually-cloned into pUC-T vector. Sequences of the eight liver-derived X gene were aligned and compared with the wild type, the ayw HBV serotype. Results indicate that the HBx protein of variants were found predominantly within the regions of amino acid positions 26-45 in N-terminus, and positions 87, 88, 116, 118, 119, 127 and 144. Sequences from six out of the eight variants were found to be identical. These accumulated sequence mutations among the eight HBx variants were found to coincide within the B-cell epitopes (positions 29-48), particularly in the HBx proline and serine rich (PSR) domain, and the T-cell epitopes regions (positions 116-127). These frequent mutations of HBV variants, rather than subtype-specific polymorphic sites, may be involved in immunoevasion.

Correlation of clinical characteristics with detection of hepatitis B virus X gene in liver tissue in HBsAg-negative, and HCV-negative hepatocellular carcinoma patients

PURPOSE

We studied the clinical features and the etiology of hepatitis B virus surface antigen (HBsAg)-negative and antibody to hepatitis C virus (anti-HCV) negative patients with hepatocellular carcinoma.

METHODS

A total of 550 patients, hospitalized with an initial diagnosis of HCC were retrospectively studied. Eighty-one of these patients were HBsAg-positive (HB group), 404 patients were anti-HCV positive (HC group). The other 65 patients were negative for both HBsAg and for anti-HCV (NBNC group). We purified HBV-X gene from HCC or non-tumorous liver tissue of 23 NBNC patients using PCR.

RESULTS

Clinical features of NBNC as compared with HB and HC patients were as follows, respectively: non-cirrhosis rate (%): 57,37,15 (P = 0.02 for HB, P < 0.00001 for HC), the proportion of patients with normal ALT concentrations (%): 59,28,10 (P = 0.0002 for HB, P < 0.00001 for HC). Forty of 59 NBNC patients (68%) had anti-HBs and/or anti-HBc (healthy controls: 29%, P < 0.00001) and two of 56 had serum HBV DNA. Twelve of 23 NBNC patients had HBV-X gene in HCC and/or non-cancerous liver tissues (52%). None of 52 had serum HCV RNA.

CONCLUSIONS

The NBNC patients with HCC had a higher frequency of non-cirrhotic liver without liver injury. The presence of the HBV-X gene in HCC suggests a possible role of past HBV infection in the development of HCC. About half of NBNC HCC is associated with seronegativity for HBsAg and positivity for the HBV-X gene in liver tissue.

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.

The long-term outcome of interferon-alpha treated and untreated patients with HBeAg-negative chronic hepatitis B

BACKGROUND/AIMS

This study aimed to evaluate the effect of interferon-alpha therapy on the long-term outcome of HBeAg-negative chronic hepatitis B.

METHODS

A cohort of 209 interferon-alpha treated and 195 untreated patients with histologically documented HBeAg-negative chronic hepatitis B were closely followed for a mean of 6 (1-13.5) years. Patients with decompensated liver disease and/or hepatocellular carcinoma at presentation were excluded.

RESULTS

Survival and complication (liver decompensation and/or hepatocellular carcinoma) -free survival were significantly worse in patients with compared to those without baseline cirrhosis and in patients older compared to those younger than 45 years (P < 10(-4)). Sustained biochemical remission was achieved in 57 treated patients. Sustained responders had significantly better survival and complication-free survival than non-sustained responders (P = 0.027 and P = 0.019, respectively) or than untreated patients (P = 0.048 and P = 0.012, respectively). Multivariate analysis showed that absence of baseline cirrhosis, younger age, and sustained biochemical remission were independently associated with an improved outcome.

CONCLUSION

In patients with HBeAg-negative chronic hepatitis B, sustained biochemical remission induced by interferon-alpha is associated with improved long-term outcome, even in the presence of cirrhosis and old age, both known factors associated with worse survival. Therefore, long-term biochemical remission appears to represent a satisfactory therapeutic target in this setting.

Molecular bases for the development of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC)

Hepatocellular carcinoma (HCC) is the most common histological form of primary liver cancer; the tumor cells having retained features of hepatocytic differentiation. It is important to emphasize the heterogeneity of the histological background on which the tumor develops. Most HCCs complicate the evolution of an active or inactive cirrhosis. However, some tumors occur on livers with minimal histological changes; the prevalence of such cases varies from one geographical region to the other; being much higher in the southern half of Africa (around 40% of HCCs) than in Asia, America and Europe, where at least 90% of HCCs are associated in the cirrhosis. This heterogeneity is probably a reflection of different environmental and genetic factors. A large number of epidemiological and molecular studies have indeed clearly demonstrated the prime importance of environmental factors to the development of primary liver cancers in humans. Chronic hepatitis B (HBV) and C (HCV) infections are major risk factors. This review will mainly analyse the impact of chronic HBV infection but it is important to emphasize the potential synergistic effects between HBV and HCV, as well as between viral infections and other environmental factors, such as alcohol, chemical carcinogens (see review by Dr Wogan) and other, still poorly defined, hormonal factors which may account for the higher incidence of the tumor in man. Finally the review by Dr Buendia highlights the emerging issue of liver-cancer genetics.

[Neoplastic disorders and organ transplantation]

INTRODUCTION

Organ transplantation is associated with an increased risk of neoplasia, which seems to be caused by the total effect of immunosuppression, i.e., the combination of factors involved, rather than by the use of a specific class of immunosuppressants. The presence and proliferation of viral oncogenes is frequently observed during this immunosuppressive state. The neoplasia in immunosuppressed patients therefore has particular histological, clinical, evolutive, and therapeutical characteristics.

CURRENT KNOWLEDGE AND KEY POINTS

The oncogenic mechanisms in immunosuppressed patients have been progressively clarified. A viral infection is associated with each type of neoplasia: thus, B lymphoma are generally associated with Epstein-Barr viral infection. Skin and uterine cervical carcinomas frequently appear after viral dysplasia due to papillomavirus. The significant increase in the incidence of Kaposi sarcoma shows the role of the immune system in the control of the infection by the human herpes virus 8, which has been recently discovered. Liver cancer is associated with a history of hepatitis B or C chronic infection.

FUTURE PROSPECTS AND PROJECTS

Post-transplantation neoplasia constitutes a major problem in patient follow-up, as the number of transplant patients has increased and their survival rate has improved. In addition, there is an increasingly powerful new generation of immunosuppressive drugs. A precise knowledge of the immune system's control mechanisms regarding neoplasic cells and viral infection is an important step in the prevention and efficient treatment of these forms of cancer. Further research into the relationship between the immune system and viral oncogenesis should therefore be considered a major aim.

Pathogenesis of hepatitis B and C-induced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is estimated to have an annual worldwide incidence of 0.25 to 1.2 million new cases per year. Both the prevalence and incidence of HCC vary markedly as a function of geography and the local prevalence of chronic viral hepatitis. Both chronic hepatitis B and chronic hepatitis C are recognized as risk factors for HCC. The prevalence of cirrhosis in individuals with HCC and chronic hepatitis B or C is reported to be 80.9% and 75.8%, respectively. HCC occurs at a lower rate in chronic viral hepatitis in the absence of cirrhosis. Moreover, hepatitis C virus (HCV) rather than hepatitis B virus (HBV) is associated with the majority of non-cirrhotic cases of HCC. It is probable that the ongoing process of hepatocyte necrosis and liver cell renewal coupled with inflammation, which is characteristic of chronic viral hepatitis, causes not only nodular regeneration and cirrhosis but also progressive genomic errors in hepatocytes as well as unregulated growth and repair mechanisms leading to hepatocyte dysplasia and, in some cases, hepatic carcinoma. Current concepts concerning virus-induced HCC are reported and discussed in the following review.

Impact of HBV, HCV and GBV-C/HGV on hepatocellular carcinomas in Europe: results of a European concerted action

BACKGROUND/AIMS

To investigate the impact of hepatitis B (HBV) and C (HCV) infections on hepatocellular carcinoma (HCC) in Europe.

METHODS

Five hundred and three patients with HCC, from six liver centers, were included. All 503 sera and 80 liver samples were tested for HBV DNA and HCV RNA by polymerase chain reaction. GBV-C/HGV RNA was also tested in 57 sera.

RESULTS

HBsAg and anti-HCV were detected in 19% and 40.1% of the patients, respectively. Serum and liver HBV DNA were detected in 82% and 91% of the HBsAg positive subjects. HBV DNA was also detected in the serum and liver of 33% and 47% of HBsAg negative patients. In this group, serum HBV DNA was more prevalent in anti-HBs and/or anti-HBc patients (47.9%), compared to those without any HBV marker (25.1%). HCV RNA was detected in 89% and 7% of anti-HCV positive and negative cases, respectively, HCV 1b being the most prevalent genotype (80%). Coinfection with HBV and HCV was shown in 20.4% of patients, while only 29% had neither HBV nor HCV GBV-C/HGV RNA was detected in only 4/57 sera.

CONCLUSIONS

This study offers the first large analysis of HCC in Europe, based on both serology and molecular tests. It demonstrates the major impact of HBV and HCV, but not of GBV-C/HGV, in liver carcinogenesis in Northern as well as Southern Europe. It also stresses the need to use viral genome detection in epidemiological studies when serological tests are negative.

Association between hepatitis B virus core promoter rearrangements and hepatocellular carcinoma

Hepatitis B virus (HBV) is the major etiological agent of hepatocellular carcinoma (HCC). Whether any particular viral variants are associated with HCC is unknown. We studied 53 Gambian patients with HCC and 33 HBsAg positive controls. A functional part of HBV core promoter and whole precore region were sequenced directly and/or after cloning. HBV DNA was amplified from sera from 27 HCC patients and in all controls. Fourteen (52%) patients and 12 (36%) controls (NS) were found to harbor an HBV strain with G to A transition mutation at position 1896 leading to HBeAg negative phenotype. Nine (33%) HCC patients and 2 (6%) controls (p < 0.01) harbored a mixture of wild type and HBV strains with deletions/insertions; strong consensus sequences for topoisomerase I breakage were located in the vicinity of these changes. In Africa, HCC is associated with HBV strains that have deletions/insertions in the HBV core promoter region.

Comparison of clinico-pathological features in hepatitis B virus-associated hepatocellular carcinoma with or without hepatitis D virus superinfection

BACKGROUND/AIMS

Hepatitis D virus superinfection in hepatitis B virus carriers produces additional damage in an already injured liver. Earlier reports noted that the development of hepatocellular carcinoma may be accelerated in hepatitis D virus-superinfected patients. This study aimed to investigate the impact of hepatitis D virus on the clinical course of hepatitis B virus-associated hepatocellular carcinoma.

METHODS

A total of 42 consecutive hepatocellular carcinoma cases seropositive for antibody against hepatitis D virus antigen (anti-HDV) were found from 1986 to 1994; the clinical manifestations, treatment and outcomes were compared with 255 consecutive hepatocellular carcinoma cases seropositive for hepatitis B virus surface antigen but seronegative for anti-HDV.

RESULTS

The mean age was 60 years in both groups of patients. Other features, including sex, duration of follow-up, presence of cirrhosis or ascites, serum biochemistry, status of HBV-e antigen, and gross and microscopic tumor appearance, were not significantly different between the two groups. Though more patients in the anti-HDV-positive group underwent active treatment (operation or transcatheter arterial chemoembolization) than those in the anti-HDV-negative group (54.8% in 42 versus 34.9% in 255 cases, p = 0.02), the cumulative 4-year survival rates (9.5% versus 9.8%) were similar. For the anti-HDV-positive hepatocellular carcinoma patients, tumor size < 5 cm and active treatment were favorable prognostic predictors associated with survival > 18 months.

CONCLUSION

Hepatitis D virus superinfection does not accelerate the development of hepatocellular carcinoma. The clinical manifestations were similar, and the outcome in anti-HDV-positive patients was not worse than in the general HBV-associated hepatocellular carcinoma patients, as long as they were diagnosed at an early stage and actively treated.

Immune response of immunocompromised children with malignancies to a recombinant hepatitis B vaccine

The aim of this study was to interpret the antibody response to hepatitis B vaccination following an intensified four-dose schedule in 140 cancer patients who presented at our clinic between January 1, 1993 and December 31, 1994. According to therapy status, the patients were divided into two groups: group A consisted of 76 patients undergoing chemotherapy and group B of 64 patients in complete remission and off treatment. The eligibility requirements were negative hepatitis B virus (HBV), HCV, and human immunodeficiency virus serologic markers. A total of four dose (20 micrograms per dose) of recombinant HB vaccine was administered intramuscularly in the deltoid region at 0, 1, 2, and 6 months. Blood from the vaccinated subjects was obtained at months 1, 2, 3, and 7 in order to measure anti-HBs titer levels. Protective anti-HBs titers were considered to be those > or = 10 mIU/mL. The overall seroconversion rate 1 month after the fourth dose was 57% (80/140 patients), and the seroconversion rates for groups A and B were 31.5% (24/76 patients) and 87.5% (56/64 patients), respectively. Our results indicated that immunocompromised children undergoing chemotherapy (although less responsive than children in complete remission and off treatment) still preserved their potential to produce protective titers of anti-HBs. On this basis we recommend (1) HB vaccination after diagnosis of malignancy in pediatric patients whenever a high prevalence of HB infection exists and (2) vaccination of patients of therapy and in complete remission.

Etiology, screening, and treatment of hepatocellular carcinoma

The prognosis with large hepatocellular carcinomas is poor, and only palliative treatment is available. Small tumors are amenable to several modes of treatment, including liver transplantation, resection, or alcohol injection, with acceptable 5-year survival rates. Although the value of screening for hepatocellular carcinoma has yet to be shown, these data, coupled with the recognition of at-risk groups and useful diagnostic techniques, might encourage the clinician to screen at-risk patients in the clinic. New imaging techniques such as ultrasonographic angiography enhanced with CO2 microbubbles, or color Doppler ultrasound, may clarify the intratumoral blood flow of small tumors.

The long-term virologic and pathologic impact of renal transplantation on chronic hepatitis B virus infection

In an attempt to evaluate the long-term reciprocal impact of renal transplantation on hepatitis B virus infection, we analyzed the clinical, virologic, and pathologic features of 151 HBsAg-positive kidney transplant recipients. The spontaneous disappearance rates of HBsAg, HBeAg, and HBV DNA during a median follow-up of 125 months (range 1 to 320) were 3, 30.6, and 3%, respectively, figures lower than in the general population. A high rate of persistent viral replication (50%) and reactivation (30%) was noted. Noteworthy was the high frequency of histologic deterioration (85.3%), accompanied by cirrhosis in 28% and by hepatocellular carcinoma in 23% of the patients with cirrhosis. Co-infection by hepatitis C and B viruses was significantly associated with histologic worsening. Liver disease was the leading cause of death (36.6%), especially in patients with cirrhosis. Despite persistent viral replication, histopathologic deterioration, and liver-related overmortality, there were paradoxically no significant differences in the survival of these 151 HBsAg-positive compared with 1247 HBsAg-negative kidney recipients--however, allograft actuarial survival was better in the former than in the latter group (P=0.0006). Chronic hepatitis B infection is not a contraindication to renal transplantation in the absence of cirrhosis. The presence of cirrhosis should lead either to dialysis continuation or to a combined liver/kidney transplantation, in the absence of viral replication.

Hepatitis B epidemiology and cultural practices in Amerindian populations of Amazonia: the Tupí-Mondé and the Xavánte from Brazil

Hepatitis B infection and disease are highly endemic in South America. Prevalences of positivity are particularly high in Amazonia, and among Amerindian peoples in particular. This paper reports the results of a seroepidemiological survey for hepatitis B virus (HBV) carried out among four Amerindian populations from the Brazilian Amazon region: Gavião, Surui, Zoro and Navate. Rates of positivity to HBV serological markers (HBsAg, anti-HBs and or anti-HBc) are very high for the four groups, ranging from 62.8 to 95.7%. It is argued that the high rates of positivity in the Amerindian groups dealt with in this study, as well as for other Amazonian populations, are related to a complex of cultural practices which enhance the likelihood of HBV transmission (bloodletting, scarification, tattooing and orally processed food, among others). The authors suggest that, due to unique patterns of interaction between sociocultural and environmental factors. HBV infection assumes a specific profile in native Amazonian societies.

Gradual accumulation of mutations in precore core region of HBV in patients with chronic active hepatitis: implications of clustering changes in a small region of the HBV core region

The sequence in the precore and core region of the hepatitis B virus (HBV) genome in the serum of five chronic active hepatitis patients at four different stages in each individual were studied by polymerase chain reaction and DNA sequencing to determine the prevalence and type of precore and core mutants in each chronic active hepatitis (CAH) patient. Gradual changes of the virus genome in each CAH patient in precore and core regions were identified. Except for the virus from one patient, the mutant viruses showed gradual changes of genome sequences, which resulted in the generation of stop codons at the precore and core region, causing the association of active hepatitis in each patient even in the presence of anti-HBe. Mutational hot spots in the core region, which includes a clustering of changes in a small region of 14 amino acids (codons 84-97 from the start of the core gene) were found in all patients. This region of mutational hot spots in the core might be a major target of cytotoxic T lymphocytes (CTL), which has evolved under the pressure of immune selections, and these mutants might play a important role in the pathogenesis of viral hepatitis.

Hepatitis B virus preC mutants in human hepatocellular carcinoma tissues

A comparative analysis of preC sequences of hepatitis B virus (HBV) in human hepatoma (hepatocellular carcinoma; HCC) tissues and non-tumoral liver samples from HCC patients was performed. Ten out of 17 HCC tissue samples exhibited an amino acid substitution at the level of the distal cysteine residue of the HBV preC region, while generation of a TAG translational stop codon was observed in 4 of these samples. Interestingly, substitution of the distal cysteine residue was not observed in non-tumoral liver (available from 8 of the 17 patients), thus suggesting either that a selection among different HBV variants occurs in HCC cells, or that modifications to the conformation and stability of the HBV capsid protein may play a role in the process of selection and escape of transformed liver cells.

Suppression of the inhibitory effect of denatured albumin on the polymerase chain reaction by sodium octanoate: application to routine clinical detection of hepatitis B virus at its infectivity threshold in serum

Ten to fifteen percent of posttransfusion viral hepatitis cases are still caused by HBV despite mandatory third generation screening procedures for HBsAg. There is thus an urgent need for a simple, time-cost-effective, but very sensitive test for routine HBV DNA detection in serum. Nested-primed PCR has been shown to detect purified HBV DNA at its infectivity threshold in serum. Since this is too labor-intensive for routine testing, we assessed the efficiency of a Fast PCR procedure, of three pairs of primers, and of thirty-five simple serum pretreatments with the aim to achieve the same sensitivity level. Using ten-fold dilution in phosphate buffered saline as pretreatment and Fast PCR for 99 cycles, we were able to detect HBV DNA at the 2 x 10(3)/ml level in serum. Using either NaOH denaturation or sodium octanoate thermoprotection as pretreatment and Fast PCR for 99 cycles, we were able to detect HBV DNA at its infectivity threshold in serum, while the classical phenol/chloroform/isoamylic alcohol/isopropanol/ethanol DNA purification procedure enabled us to reach the 10 virus particles/ml level. These results suggest that denatured albumin is responsible for the well known inhibitory effect of serum proteins on Taq polymerase. Because of its simplicity and its lower risk of sample-to-sample cross-contamination, the sodium octanoate thermoprotection method was chosen for routine clinical detection of HBV in serum. The clinical usefulness of this approach is demonstrated by the results obtained with HBsAg-negative acute hepatitis B incubation sera and with anti HBe-positive chronic hepatitis B sera.

Oncogenic activation of cyclin A

Cyclin A associates with both the p34 cdc2 and p33 cdk2 kinases and is involved at two major check-points (G1-S and G2-M) of the cell cycle. The cyclin has been identified in multimeric protein complexes that incorporate the E2F transcription factor, the p33 cdk2 kinase, and p107, which is related to the retinoblastoma protein. Therefore, cyclin A provides a link between studies on the cell-cycle machinery and those aiming to elucidate the modulation of cell proliferation and regulation of gene expression by oncogenes and growth-suppressor proteins. The modification of cyclin A expression in a human liver cancer by the insertion of hepatitis B viral DNA into the cyclin A gene, and binding of cyclin A to the oncogenic E1A viral protein in adenovirus-infected cells suggest that the cyclin is implicated in human carcinogenesis. In addition, cyclin A might also be considered as a marker for tumor-cell proliferation in oncology. With these views in mind, it is now important to extend these observations to other types of cancer.

Hepatitis C virus associated primary hepatocellular carcinoma in a noncirrhotic liver

The case of a 71-year-old man with a primary hepatocellular carcinoma in a non-cirrhotic liver is reported. There were no risk factors of hepatocellular carcinoma (HCC)-like liver cirrhosis, alcohol drinking, tobacco smoking, exposure to vinyl chloride, thorotrast, aflatoxin or alpha 1-antitrypsin deficiency. Serologically, the patient was positive for antibodies to the hepatitis B virus (anti-HBc, anti-HBs) and for anti-hepatitis C virus (HCV) antibodies. Virologically, positive and negative strands of HCV RNA could be detected in the patient's serum and tumorous liver tissue by reverse transcription polymerase chain reaction as a sign of persistent HCV replication. Histologically, the HCC was completely surrounded by liver tissue which showed the signs of nodular regenerative hyperplasia. Indeed, the mechanism of hepatocarcinogenesis remains to be clarified. However, this case supports the observation that HCC may also develop in patients with HCV infection without preexisting liver cirrhosis.

Hepatitis B X-gene expression in hepatocellular carcinoma

A RNA-PCR method and different sets of primers were used to investigate the expression of different hepatitis B (HB) virus genes at the RNA level. We tested paired samples (tumor and non-tumor) from the liver tissues of 48 Taiwanese patients with primary hepatocellular carcinoma (HCC). By using a set of primers which spanned the sequences of the S-gene, we found expression in only 2 patients. In one HBs-RNA was only detected in the tumor tissue and in the other only in the surrounding non-tumor tissue. Using primers covering the C-gene, expression was found in 7 patients. In 2 of these RNA was detected in both the tumor and the surrounding tissue, in 2 in the tumor tissue, and in 3 in the surrounding tissue only. Finally, when primers spanning the X-gene sequences were used, RNA was detected in 40/48 patients. In 33 of these cases HBx-RNA was detected in both tumor and non-tumor tissue, in 3 patients in tumor tissue only, and in 4 in the surrounding tissue. Among the cases in which HBc and HBs-RNA was expressed, all showed HBx expression also. These data indicate that the expression of the HBx gene in HCC may play an important role in hepatocarcinogenesis.

Latent hepatitis B virus infection in childhood hepatocellular carcinoma. Analysis by polymerase chain reaction

The presence of hepatitis B virus (HBV) has been evaluated in liver specimens from 11 children with primary liver tumors and negative results of serologic testing for HBV markers. HBV-DNA sequences were detected by the polymerase chain reaction procedure, using different sets of oligonucleotide primers from highly conserved regions of HBV genome. Two of three children with histologic diagnosis of hepatocellular carcinoma were positive for HBV-DNA in the liver, whereas the remaining children, including six patients with hepatoblastoma, one patient with hemangioma, and one patient with hamartoma, were negative. These findings support the hypothesis of a primary role of HBV in the development of hepatocellular carcinoma in children from nonendemic areas and without overt HBV infection.

Sequence analysis of the hepatitis B virus pre-C region in hepatocellular carcinoma [HCC] and nontumoral liver tissues from HCC patients

We investigated whether replication-competent pre-C/C defective mutants of hepatitis B virus (HBV) are detectable in primary human hepatocellular carcinoma (HCC) tissues from patients of a geographic area endemic for such mutants. DNAs extracted from formalin-fixed paraffin-embedded HCC samples were checked for the presence of specific HBV DNA sequences using the polymerase chain reaction (PCR). Amplified pre-C regions from nine HCC samples were directly sequenced as were samples of nontumoral liver tissues from five of these patients. The data show that hypervariable distal pre-C sequences were present in all nine HCC samples; this high variability was dependent on point mutations, which led to amino acid substitutions in nearly all cases. Interestingly, seven of the nine HBV DNA-positive samples from HCC tissues (but not samples from peritumoral liver tissue) showed mutations leading to amino acid substitution at the level of a distal cysteine residue. No mutation generating a translationally defective pre-C/C region was detectable in the tumor samples. Otherwise, in four of the six nontumoral liver tissues available from the same patients, a pre-C sequence with an in-frame TAG stop codon was detectable, although in three cases as a component of mixed population.

Anti-HCV antibodies and hepatocellular carcinoma. Relationship in a medium-risk population

By means of an accurate immunoenzymatic assay, the prevalence was studied of antibodies to hepatitis C virus (HCV) in three different populations: 74 patients affected with hepatocellular carcinoma (HCC) on preexisting cirrhosis, 82 patients with liver cirrhosis but with no apparent neoplasm, and 70 control subjects, hospitalized for various conditions, of internal medicine or geriatric interest. 70.2% of HCC patients exhibited anti-HBC antibodies, versus 47.5% of cirrhotic subjects with no tumor and 7.1% of controls. Such results suggest the possible role of HCV in the etiopathogenesis of HCC, and its possible synergy with other agents-e.g., hepatitis B virus, alcohol--in causing chronically injured hepatocytes to become neoplastic.

The detection of hepatitis B virus (HBV) in HBsAG negative individuals with primary liver cancer

The importance of chronic hepatitis B virus (HBV) infection in the development of primary liver cancer has been established by epidemiological studies. However, the evidence for a direct role of the virus in liver carcinogenesis is still tentative. In addition, the findings of HBV DNA sequences in HBsAg-negative subjects with liver cancer has been reported, although it is controversial. Here we report the use of the polymerase chain reaction to detect HBV DNA in the serum and liver of HBsAg-negative patients. This technique allows both for the detection and cloning of HBV variants. In addition, the demonstration of HBV DNA and RNA molecules in HCC of HBsAg-negative individuals as determined by standard techniques reinforces the role of HBV in the pathogenesis of this tumor.

Hepatitis B virus variant, with a deletion in the preS2 and two translational stop codons in the precore regions, in a patient with hepatocellular carcinoma

We analyzed hepatitis B virus (HBV) genomes obtained from serum samples and liver biopsy specimen of a chronic HBsAg/anti-HBe carrier with hepatocellular carcinoma (HCC). Before the liver biopsy, performed at the time of HCC diagnosis, the patient had been followed for 2 years; the serum samples collected in that period resulted negative for HBV-DNA dot blot hybridization. The hepatic DNA was at first examined by Southern blot, but no HBV sequence was detected. Polymerase chain reaction (PCR) amplification revealed the presence of HBV genomes in DNA extracted from the liver tissue and from two serum samples collected, respectively, 1 and 2 years before the biopsy. Direct sequence of the amplified preC/C and preS regions showed that the viral populations present in serum and liver were identical and that they had a 34 nucleotide deletion in the preS2 region, while the preC region presented two mutations each introducing a translational stop codon, one at the carboxy terminal end and the other at the second codon of the region, both able to prevent HBeAg expression. These results identify a new HBV variant which was selected during a chronic infection, and had very low levels of replication as shown by its detection only after PCR amplification.

Polymerase chain reaction to detect hepatitis B virus DNA and RNA sequences in primary liver cancers from patients negative for hepatitis B surface antigen

BACKGROUND AND METHODS

The role of hepatitis B virus (HBV) in the course of patients with primary liver cancer who are negative for hepatitis B surface antigen has been debated. We used the polymerase chain reaction to evaluate 28 such patients for the presence of DNA and RNA sequences of the virus; 22 of these patients had associated cirrhosis. The patients were from areas with different prevalences of HBV infection (South Africa, Italy, France, and Japan).

RESULTS

Antibodies to the surface and core antigens of HBV were detected in 10 of the 23 patients tested. HBV DNA sequences were detected in 17 of the 28 patients, including 8 of the 10 with HBV antibodies and 6 of 13 without HBV serologic markers. HBV RNA molecules were found in four of five tumors tested.

CONCLUSIONS

Our investigation indicates that transcriptionally active HBV genomes are present in various geographic areas among patients with liver cancer who are negative for hepatitis B surface antigen. This observation is consistent with an etiologic role for the virus in the development of these tumors.

Replication of hepatitis B virus in a hepatocellular carcinoma

Hepatitis B virus transcripts and DNA from paired samples of neoplastic and nonneoplastic liver tissue of HBsAg seropositive patients were analyzed. The data obtained support the view that transcription of integrated DNA is frequent, both in neoplastic as well as in nonneoplastic liver tissue. In the case of one patient, integrated and free forms of hepatitis B virus DNA were detected in the tumor. Complete cycles of viral replication in this tumor were suggested by the following markers: (i) DNA and RNA intermediates expected to occur during replication of the viral genome, (ii) HBcAg and HBsAg, (iii) core and Dane particles. Viral DNA cloned from tumor tissue was proven to be replication competent in a transient replication assay. Five independent clones of viral DNA were established and found to be closely related at the nucleotide level. A preX open reading frame and a stop codon within preC were common features. In tissue surrounding the tumor, a nonreplicative state of virus infection prevailed, characterized by free viral DNA exclusively of the covalently closed, circular form. The replication of the viral DNA appeared to be blocked at the level of transcription.

Aflatoxin B1 formamidopyrimidine adducts in human hepatocarcinogenesis: a preliminary report

The presence of aflatoxin-B1-formamidopyrimidine, a persistent aflatoxin-deoxyribonucleic acid (DNA) adduct, was investigated in vivo by immunohistochemical analysis in 14 paired hepatocellular carcinoma and nontumorous human liver tissue sections using a monoclonal anti-aflatoxin-B1-formamidopyrimidine antibody. Nuclear and cytoplasmic accumulations of adducts were found in 4 of 14 nontumorous specimens but in none of 14 tumorous tissues and in none of three normal control livers. In vitro adduct formation and cellular DNA was investigated with a modified DNA immunoblot assay. These studies revealed (a) no significant difference in the amount of adduct formed by DNA samples with or without integrated hepatitis B virus DNA, (b) no difference in the amount of adduct formed with DNA from either tumorous or nontumorous tissues from a given individual, and (c) remarkable and reproducible differences in the capacity of DNA from different individuals to form in vitro adducts. Our DNA immunoblot assay will facilitate further studies on the molecular role of aflatoxin-B1-form-amidopyrimidine adducts in human hepatocarcinogenesis.

Prevalence of antibodies to hepatitis C virus in Spanish patients with hepatocellular carcinoma and hepatic cirrhosis

The prevalence of antibodies against hepatitis C virus (HCV) was investigated in 96 patients with hepatocellular carcinoma, 106 patients with liver cirrhosis without evidence of cancer, and 177 controls without liver disease. 75% of patients with hepatocellular carcinoma had HCV antibodies (anti-HCV), a significantly higher proportion than that observed in patients with cirrhosis (55.6%), or controls (7.3%). The prevalence of anti-HCV was significantly higher in patients with alcoholic cirrhosis and hepatocellular carcinoma (76%) than in patients with alcoholic cirrhosis alone (38.7%) whereas in patients with cryptogenic cirrhosis there was no significant difference between those with and without primary liver cell cancer (81.4% and 77.5%, respectively). These results indicate that HCV infection may have a role in the pathogenesis of hepatocellular carcinoma, even in patients with chronic liver disease apparently related to other agents such as alcohol, and that this recently identified hepatitis virus may be found in a large proportion of patients with cryptogenic cirrhosis.

Hepatocellular carcinoma: molecular biology of its growth and relationship to hepatitis B virus infection

Hepatocellular carcinoma is a very common tumor worldwide and is associated with high mortality rates. Evidence that the development of hepatocellular carcinoma is related to chronic HBV infection has accumulated from epidemiologic studies, information from animal and cell culture models, and molecular biologic evidence that HBV components can be found within hepatocellular carcinoma tissue. Integration of HBV DNA within host liver cell chromosomes may be a crucial step in the development of hepatocellular carcinoma. Integration is associated with disruption of both structure and function of DNA at the site of integration. The study of individual examples of HBV DNA integration in hepatocellular carcinoma tissue illustrates possible mechanisms of hepatocarcinogenesis by HBV. In many cases, activation of various growth factors has been found in association with HBV DNA integration including IGF II, oncogenes such as c-myc, and novel growth factors such as the retinoic acid receptor. A clearer understanding of the mechanisms involved may allow for possible therapeutic interventions in the future, or perhaps even the prevention of hepatocellular carcinoma.