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HBV Exposure May Increase HCC Risk Among HCV+ with Cirrhosis, Japan study reports
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"Antibody to Hepatitis B Core Antigen and Risk for Hepatitis C-Related Hepatocellular Carcinoma"
A Prospective Study
Kazuki Ikeda, MD; Hiroyuki Marusawa, MD, PhD; Yukio Osaki, MD; Takefumi Nakamura, MD, PhD; Naoto Kitajima, MD, PhD; Yukitaka Yamashita, MD, PhD; Masatoshi Kudo, MD, PhD; Tosiya Sato, PhD; and Tsutomu Chiba, MD, PhD
From Kyoto University, Kyoto, Japan; Osaka Red Cross Hospital, Kitano Hospital, and Kinki University, Osaka, Japan; Kasai Municipal Hospital, Hyogo, Japan; and Wakayama Red Cross Medical Center, Wakayama, Japan.
Annals Of Internal Medicine, 1 May 2007 Volume 146 Issue 9 Pages 649-656
"EDITOR Comments: These investigators prospectively studied patients with chronic HCV infection and evidence of occult HBV infection (negative results for hepatitis B surface antigen and HBV DNA but positive results for antibody to hepatitis B core antigen [anti-HBc] on serologic testing). Patients with HCV-related cirrhosis and positive results for anti-HBc on serologic testing were at high risk for HCC. Anti-HBc positivity was associated with increased risk for HCC, even in patients with a virologic response to interferon therapy."
ABSTRACT
Background: Previous exposure to hepatitis B virus (HBV) and occult HBV infection may have an important role in the development of hepatocellular carcinoma (HCC) in patients with chronic liver disease related to hepatitis C virus (HCV).
Objective: To prospectively study the association between antibody to hepatitis B core antigen (anti-HBc) and clinical outcomes in patients with HCV-related chronic liver disease.
Design: Prospective observational study.
Setting: Kyoto University Hospital and 14 regional core hospitals in Japan.
Participants: 872 patients with chronic HCV infection (597 with chronic hepatitis and 275 with cirrhosis).
Measurements: Incidence of HCC on follow-up (from 1995 to 2005).
Results: Only 846 of the 872 enrolled patients were followed. Hepatocellular carcinoma occurred in 237 of 846 patients (28.0%) during follow-up. Among patients with cirrhosis, HCC was diagnosed in 85 of 141 patients (60.3%) with anti-HBc and 58 of 129 patients (45.0%) without HBV-related serologic markers. Of 224 patients with chronic hepatitis who had interferon monotherapy, 92 (41.1%) had sustained or transient disappearance of HCV RNA. None of the anti-HBc-negative patients who had a virologic response to interferon therapy developed HCC, whereas cancer was diagnosed in 4 of 37 anti-HBc-positive patients (10.8%) with a virologic response to interferon. On multivariate analysis using a Cox proportional hazards model, anti-HBc-positive results on serologic testing was an independent risk factor in patients with cirrhosis (incidence rate ratio, 1.58 [95% CI, 1.12 to 2.22]).
Limitations: The study included only 1 assessment of smoking and alcohol consumption at study entry and did not precisely determine the duration of smoking or alcohol use.
Conclusions: Anti-HBc-positive results on serologic testing are a marker of high risk for HCC among patients with HCV-related cirrhosis. Interferon therapy might be less effective in preventing HCC among patients with chronic hepatitis C who are anti-HBc-positive than in those with chronic hepatitis C who are anti-HBc-negative.
Background
Hepatocellular carcinoma (HCC) is one of the most common types of cancer worldwide, and its incidence has been increasing (1, 2). In Japan, an endemic area for hepatitis B virus (HBV) and hepatitis C virus (HCV), it is well known that more than 75% of cases of HCC are attributable to HCV-related chronic liver disease, and nearly 15% are attributable to HBV-related liver disease (3). Several reports have focused on the clinical role of HBV as a unique infection, in which HBV DNA is detectable in the liver despite the absence of serum hepatitis B surface antigen (HBsAg) (4-6). It is increasingly recognized that after a person is exposed to HBV, infection persists in the liver for a prolonged period (7-10). This unique persistent infection, known as occult (or latent) HBV infection, is characterized by HBV DNA in the liver but no HBsAg in the serum (11-13). In most cases, antibody to hepatitis B core antigen (anti-HBc) is detectable, and thus anti-HBc is believed to be a surrogate marker for latent carriers (14). In fact, we recently showed that HBV infection invariably occurred through grafts from anti-HBc-positive donors in HBV-naive recipients through living-donor liver transplantation (15). In addition to our data, other reports showing frequent HBV transmission from anti-HBc-positive cadaveric donors to recipients indicate that most healthy persons who are positive for anti-HBc, even at low titers, have latent HBV infection in liver tissue (11, 16-18). Indeed, we have shown that most anti-HBc-positive healthy persons have a latent episomal form of HBV infection accompanied by ongoing viral replication (19, 20). In contrast, the prevalence of latent HBV infection in anti-HBc-positive patients with HCV-related chronic liver disease, including chronic hepatitis, cirrhosis, and HCC, remains controversial (21). However, several reports have revealed that the HBV genome is frequently detectable in liver tumors in anti-HBc-positive, HBsAg-negative patients with HCV-related liver disease, which suggests that occult HBV infection may contribute to the progression of liver damage and the development of HCC in HCV-positive patients (14, 22-27).
In a large-scale retrospective study of the prevalence of anti-HBc among 2014 patients with chronic HCV infection, we found that nearly 50% of patients with HCV-related liver disease had anti-HBc (28). Moreover, we found a strong correlation between the prevalence of anti-HBc and the clinical progression of liver disease. The prevalence of anti-HBc was approximately 60% in patients with HCV-related HCC (28). This high prevalence of anti-HBc in HCV-positive patients, particularly those with HCC, strongly suggests that previous exposure to HBV plays an important role in the development of HCC in patients with HCV-related chronic liver disease. Therefore, we performed a prospective study to determine whether previous exposure to HBV affects the clinical course, especially in development of HCC, in patients with chronic HCV infection.
Patients
Patients with chronic HCV infection who presented to Kyoto University, Kyoto, Japan, and 14 affiliated core hospitals from May 1995 to June 1995 were enrolled. To be eligible, patients had to have serologically confirmed HCV infection without HBsAg and HBV DNA in sera. All patients had been followed with biochemical tests, including a-fetoprotein, and ultrasonography or computed tomography (CT) every 3 to 6 months before and after enrollment. We excluded patients who had elevated a-fetoprotein levels or those in whom HCC had been diagnosed before enrollment. As a result, 872 patients with chronic HCV infection were enrolled. We discontinued follow-up in patients who moved from the study districts but included their clinical data until they moved. The end of follow-up was defined as the date of diagnosis of HCC, date of death, date of move from the study district, or the closing date of the study (15 May 2005).
A total of 384 patients were classified into the hepatitis group or cirrhosis group on the basis of histologic findings on liver biopsy. The differential diagnosis of cirrhosis or hepatitis was made in the remaining 488 patients by using the cirrhosis discriminant score (29, 30). This score is based on 3 laboratory variables: platelet count, alanine aminotransferase-aspartate aminotransferase ratio, and prothrombin time. It has been shown to be highly sensitive in identifying cirrhosis in patients with HCV infection. In accordance with the original definition, patients with a high score (>8) were classified into the cirrhosis group. Patients with ascites confirmed by ultrasonography or CT or previous variceal bleeding were given a diagnosis of cirrhosis, regardless of their score, because these findings are strong indicators of portal hypertension and most likely cirrhosis. As a result, 597 (68.5%) patients had a diagnosis of chronic hepatitis and 275 (31.5%) patients had a diagnosis of cirrhosis at the time of enrollment. The patients had regular clinical assessments, biochemical tests, and ultrasonography or CT of the liver every 3 to 6 months during the follow-up period.
Patients were stratified into 3 categories according to their smoking habits: nonsmokers, light smokers who smoked fewer than 20 pack-years, and heavy smokers who smoked 20 pack-years or more. Similarly, we stratified patients into 3 categories according to their drinking habits: nondrinkers, moderate drinkers with an average ethanol intake less than 30 g/d, and heavy drinkers with an average ethanol intake greater than 30 g/d. Information on average alcohol intake was based on the patient's drinking habits during the 15 years before study entry.
Results
Characteristics of Patients at Enrollment
We followed 846 of the 872 enrolled patients. The remaining 26 patients were excluded from the analysis. Twenty-one patients in the hepatitis group and 4 patients in the cirrhosis group did not return to the hospital, and 1 patient with cirrhosis was confirmed as having HCC 1 month after study enrollment. Table 1 shows the clinical features of 846 patients at the time of enrollment. Results on anti-HBc testing were positive in 251 of 576 (43.6%) patients in the hepatitis group and 141 of 270 (52.2%) patients in the cirrhosis group. The proportion of patients with anti-HBc was 8.6% (95% CI, 1.4% to 15.8%) higher in the cirrhosis group than in the hepatitis group, which is consistent with our previous report (28). Among patients with anti-HBc, 46.6% were also positive for anti-HBs. There were no major differences between background characteristics of patients with and those without anti-HBc in the hepatitis or cirrhosis group. During follow-up, 86 patients died of causes unrelated to HCC and 138 died of HCC. Consequently, the mean follow-up for patients who did not experience an event, such as HCC or death unrelated to HCC, was 9.5 years (SD, 1.6) and 9.7 years (SD, 0.9) in the hepatitis and cirrhosis groups, respectively.
Incidence of HCC in Patients with Chronic Hepatitis or Cirrhosis
At enrollment, no patient had HCC or any suspicious space-occupying lesion on ultrasonography or CT. Hepatocellular carcinoma developed in 237 of the 846 patients (28.0%) at an average follow-up of 4.66 years (SD, 2.67). The cumulative incidence of HCC was 11.0% at 3 years, 18.1% at 5 years, 29% at 7 years, and 45.6% at 10 years. The incidence of HCC increased steadily up to 10 years. On the basis of the classification of chronic liver disease at study entry, 94 of 576 patients with hepatitis (16.3%) and 143 of 270 patients with cirrhosis (53.0%) developed HCC during follow-up.
Table 2 shows the incidence rate ratio of HCC for each baseline characteristic. Every incidence rate was calculated on the basis of person-years. In patients with hepatitis, male sex, age older than 64 years, and smoking were shown to be risk factors for HCC, but alcohol intake was not shown to be a risk factor. In patients with cirrhosis, anti-HBc positivity and male sex were shown to be risk factors for HCC. On analysis according to anti-HBs positivity, the incidence of HCC was not substantially higher in patients who were positive only for anti-HBc than in those who were positive for anti-HBc and anti-HBs (data not shown).
Risk for HCC in Interferon-Treated Patients
Two hundred twenty-four of 576 patients with hepatitis received treatment with interferon. Most patients (90.2%) completed treatment with interferon before 1996, and all patients received natural interferon-a or interferon-β monotherapy according to protocols within the range covered by public health insurance in Japan. Of the 224 interferon-treated patients with hepatitis, 53 (23.7%) achieved a sustained virologic response, 39 (17.4%) had relapse, and 132 (58.9%) did not respond (Appendix Figure). None of the anti-HBc-positive patients with a sustained virologic response developed increases in alanine aminotransferase level or had detectable HBV DNA in their sera after HCV eradication. Thirty-five interferon-treated patients (15.6%) developed HCC during follow-up, and the mean interval between the end of therapy and detection of HCC was 7.06 years (range, 6.0 to 11.0 years). The timing of interferon treatment did not differ between patients who eventually developed HCC and those who did not.
The incidence of HCC was 1.9% in patients with a sustained virologic response, 7.7% in patients who had relapse, and 23.5% in patients who did not respond. The mean interval between the end of interferon therapy and development of HCC did not differ among patients with a sustained virologic response, those who had relapse, and those who did not respond substantially (8.0, 6.7, and 6.3 years, respectively). Of note, HCC developed in 1 patient with a sustained virologic response and 3 who had relapse. Patients with a sustained or transient response to interferon who had HCC included 3 men and 1 woman whose mean age was 62.75 years (range, 52 to 72 years). Thus, age and sex in patients with HCC who responded did not differ from those who did not develop HCC. The mean interval between the end of interferon therapy and detection of HCC in patients with HCC who responded was 8.9 years (range, 7.4 to 9.5 years), which did not differ substantially from that in patients with HCC who did not respond.
The Figure shows the incidence of HCC in patients with sustained virologic response, those who had relapse, and those who did not respond, by anti-HBc status. No patient with a virologic response and no anti-HBc developed HCC, whereas 4 patients who responded but had anti-HBc developed HCC during follow-up. These findings indicate that interferon-treated patients with anti-HBc who responded were at greater risk for HCC than were those who did not have anti-HBc in their sera. Accordingly, even among patients with a virologic response to interferon therapy, patients with anti-HBc were more likely than those without anti-HBc to develop HCC.
Multivariate Analyses of Risk Factors for HCC
To identify the effect of anti-HBc on the development of HCC, multivariate analyses were performed by using a Cox proportional hazards model that included anti-HBc positivity on serologic testing, sex, age, smoking, alcohol consumption, and response to interferon therapy (Table 3). In patients with HCV-related cirrhosis, multivariate analysis showed that an anti-HBc-positive result on serologic testing had an incidence rate ratio of 1.58 (CI, 1.12 to 2.22). The apparent suppressive effect of moderate alcohol consumption on HCC requires additional study because only 27 patients in this category were included. Among patients with chronic hepatitis, an anti-HBc-positive result on serologic testing had an incidence rate ratio of 1.03 (CI, 0.66 to 1.56), and male sex, age, smoking, and nonresponse to interferon therapy were associated with risk for HCC.
Discussion
In a previous study, we retrospectively showed that anti-HBc is detectable in approximately 50% of patients with HCV-related chronic liver disease who lacked HBsAg (28). Of note, the proportion of patients who were positive for anti-HBc increased in association with the progression of liver disease, and accordingly the prevalence of anti-HBc was substantially higher in patients with HCC than in those with chronic hepatitis or cirrhosis. Many published reports support our observation that the presence of anti-HBc in the serum of patients with HCV-related HCC is a common clinical finding, which suggests that previous exposure to HBV may be a risk factor for HCC in patients with HCV-related chronic liver disease (34, 35). However, all of those findings were obtained from retrospective studies and were not confirmed prospectively.
In this study, we conducted a long-term prospective assessment of many patients with HCV-related chronic liver disease. We showed that HCV-positive patients with cirrhosis who had anti-HBc in serum had a much higher risk for HCC than those without anti-HBc. Moreover, in multivariate analysis using the Cox proportional hazards model, we found that positivity for anti-HBc increased the risk of HCC by 1.58 times in HCV-positive patients with cirrhosis.
An important point of our study is that all of the anti-HBc-positive patients lacked HBsAg and HBV DNA in sera; such patients are considered to have had previous exposure to HBV. However, we previously demonstrated that most anti-HBc-positive healthy persons had latent infection with an episomal form of HBV accompanied by ongoing viral replication (19, 20). Consistent with observations in such persons, the HBV genome is frequently detected in HCC tissues of anti-HBc-positive patients with HCV-related chronic liver disease (22-27, 36, 37). These findings imply that the presence of occult HBV infection in the liver of patients with anti-HBc might be common and that the potential oncogenic role of anti-HBc-positive results on serologic testing is attributable to such infection. The mechanism by which occult HBV infection could contribute to hepatocarcinogenesis is unknown. One study revealed that HCC in the setting of occult HBV infection frequently shows clonal integration of HBV DNA into the host genome (38). Moreover, selective expression of a mutated X gene product from HBV DNA integrated into genomes has been shown in HCC tissues in HBsAg-negative patients (39). Thus, one possibility is that occult HBV infection in HCV-positive patients plays a role in the development of HCC through expression of oncogenic viral protein.
In contrast to patients with cirrhosis, the cumulative incidence of HCC in anti-HBc-positive patients with hepatitis did not differ from that in anti-HBc-negative patients with hepatitis. This may be due to the overall low incidence of HCC during follow-up among patients in the hepatitis group compared with those in the baseline cirrhosis group. The incidence of HCC in patients with hepatitis and anti-HBc was higher than in patients without anti-HBc but was not substantial during follow-up. Accordingly, failure to show anti-HBc-positive results on serologic testing as a substantial risk factor for HCC in patients with hepatitis may be due to the relatively short follow-up for patients with hepatitis. A longer observation period may be required to reveal a substantial association between anti-HBc-positive results on serologic testing and development of HCC in patients with HCV-related hepatitis. It is well known that interferon treatment reduces the risk for HCC in patients with HCV-related liver disease (40-42). However, several investigators have reported that HCC was still observed in patients with a sustained response to and in those with relapse after interferon treatment, although a substantial decrease in the incidence of HCC has been achieved in those patients (43-46).
The reason that HCC develops in patients who have a virologic response to interferon therapy remains unclear. We found less effect of interferon therapy for preventing HCC among patients with a virologic response who had positive results on serologic testing for anti-HBc. Indeed, no patient with a virologic response who did not have anti-HBc developed HCC, whereas 4 patients with anti-HBc who responded developed HCC during follow-up. Our findings agree with those of a retrospective cohort report showing that interferon treatment, regardless of virologic response, reduced the risk for HCC mainly in HCV-infected patients who had no evidence of previous exposure to HBV infection (41). Of interest, it was recently reported that integrated HBV DNA was detected in 4 of 7 patients with HCC who had been cured of HCV infection by interferon monotherapy (47). Together, these observations suggest that occult HBV infection in liver tissue may play a role in hepatocarcinogenesis among patients who responded to interferon therapy, even after clearance of HCV infection.
The higher risk for HCC in anti-HBc-positive patients who responded to interferon therapy has important clinical implications-namely, the need for intensive and long-term follow-up even after clearance of HCV infection by interferon therapy. We found no statistical difference in the cumulative risk for HCC among patients with a sustained virologic response, those who had relapse, and those who did not respond. Studies with more interferon-treated patients are required to reach a definitive conclusion.
In conclusion, we show that anti-HBc-positive patients with HCV-related cirrhosis had a higher risk for HCC than did those without HBV serologic markers. When the possibility is considered that most patients with anti-HBc-positive results on serologic testing have occult HBV infection in liver tissue, our findings suggest that latent HBV infection has a role in the development of HCC in patients with HCV-related chronic liver disease.
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