The presence of multiple NS5A RASs is associated with the outcome of sofosbuvir and ledipasvir therapy in NS5A inhibitor-naïve patients with chronic HCV genotype 1b infection in a real-world cohort.

It is unclear whether multiple nonstructural (NS) 5A resistance-associated substitutions (RASs) correlate with the outcome of sofosbuvir (SOF) and ledipasvir (LDV) therapy. We investigated the effects of multiple NS5A RASs in NS5A inhibitor-naïve patients with chronic hepatitis C virus genotype 1b infection treated with SOF/LDV. In 313 patients treated with SOF/LDV, we assessed the effects of multiple NS5A RASs on the sustained virological response (SVR). RASs at L28, R30, L31, Q54, P58, Q62, A92, and Y93 in the NS5A region were examined by direct sequencing. The prevalence of RASs was as follows: 2.6% at L28, 8.7% at R30, 6.1% at L31, 48.7% at Q54, 9.9% at P58, 9.9% at Q62, 5.1% at A92, 13.8% at Y93, and 19.2% at L31 or Y93. A total of 133 patients had no RASs. SVR was achieved in 98.7% of the patients. SVR rates significantly differed between patients with and without the L31 or Y93 RAS (93.0% [53/57] vs 100% [250/250], P = .0011). In addition, among patients with the L31 or Y93 RAS, 29.8%, 45.6% and 24.6% had one, two and three or more NS5A RASs, respectively. The SVR rate was significantly lower in patients with the L31 or Y93 RAS with more than three NS5A RASs compared to those with fewer than three NS5A RASs (71.4% [10/14] vs 100% [43/43], P = .0025). Although the prevalence of multiple NS5A RASs at baseline was low in NS5A inhibitor-naïve patients, the presence of multiple NS5A RASs was associated with the effectiveness of SOF/LDV therapy.

Low incidence of hepatitis B virus reactivation and subsequent hepatitis in patients with chronic hepatitis C receiving direct-acting antiviral therapy.

To determine the clinical characteristics of hepatitis B virus (HBV) reactivation in patients undergoing interferon-free antihepatitis C virus (HCV) therapy, we examined HBV DNA in 25 HBV co-infected patients and 765 patients with resolved HBV infection during and after treatment with direct-acting antiviral agents (DAAs). Among those with HCV genotype 1, asunaprevir plus daclatasvir was administered to 160 patients, sofosbuvir (SOF) plus ledipasvir to 438 patients and paritaprevir plus ombitasvir and ritonavir to 25 patients. In total, 167 patients with genotype 2 were treated with SOF plus ribavirin. Three patients with an HBV DNA level ≥2000 IU/mL were treated with entecavir before anti-HCV therapy, without reactivation of HBV. In 3 of 22 (12%) HBV surface antigen (HBsAg)-positive patients with an HBV DNA level <2000 IU/mL, the viral load increased during treatment. However, hepatitis flare did not occur in these patients. There was no significant difference in clinical history between patients with and without HBV reactivation. Among 765 patients with resolved HBV infection, HBV reactivation occurred in 1 (0.1%) patient after initial resolution, whose HBV DNA level spontaneously decreased after DAA therapy. We compared anti-HBs titres at baseline with those at post-DAA therapy in 123 patients without HBsAg. There was no significant difference in anti-HBs levels between the two points (P = .79). In conclusion, HBV reactivation was rare in HBsAg-negative patients treated with DAA therapy. Additionally, hepatitis did not occur in HBV-reactivated patients with a baseline HBV DNA level <2000 IU/mL before DAA therapy.

Significant background rates of HBV and HCV infections in patients and risks of blood transfusion from donors with low anti-HBc titres or high anti-HBc titres with high anti-HBs titres in Japan: a prospective, individual NAT study of transfusion-transmitted HBV, HCV and HIV infections.

BACKGROUND: The Japanese Red Cross (JRC) conducted a prospective study to evaluate the frequency of transfusion-transmitted HBV, HCV and HIV infections to assess the risk of transfusion of blood components routinely supplied to hospitals. STUDY DESIGN AND METHODS: Post-transfusion specimens from patients at eight medical institutes were examined for evidence of infection with HBV (2139 cases), HCV (2091) and HIV (2040) using individual nucleic acid amplification testing (NAT). If these specimens were reactive, pre-transfusion specimens were also examined for the virus concerned by individual NAT. In the event that the pre-transfusion specimen was non-reactive, then all repository specimens from implicated donors were tested for the viruses by individual donation NAT. In addition, a further study was carried out to evaluate the risk of transfusion of components from donors with low anti-HBc titres or high anti-HBc with high anti-HBs titres. RESULTS: Transfusion-transmitted HCV and HIV infections were not observed. One case of post-transfusion HBV infection was identified (rate, 0·0004675; 95% CI for the risk of transmission, 1 in 451-41,841). The background rates of HBV, HCV and HIV infections in patients prior to transfusion were 3·4% (72/2139), 7·2% (150/2091) and 0% (0/2040), respectively. Sixty-four anti-HBc- and/or anti-HBs-reactive blood components were transfused to 52 patients non-reactive for anti-HBc or anti-HBs before and after transfusion (rate, 0; 95% CI for the risk of transmission, <1 in 22). CONCLUSION: This study demonstrated that the current criteria employed by JRC have a low risk, but the background rates of HBV and HCV infections in Japanese patients are significant.

Add-on combination therapy with adefovir dipivoxil induces renal impairment in patients with lamivudine-refractory hepatitis B virus.

Combination therapy with adefovir dipivoxil (ADV) and lamivudine (LAM) is recommended for patients infected with LAM-refractory hepatitis B virus (HBV). However, the effects of such therapy on renal function and serum phosphorus levels have not been fully evaluated. Combination therapy with ADV and LAM was given to 37 patients infected with LAM-refractory HBV, including 17 with hepatic cirrhosis. Serum HBV DNA levels decreased to below 2.6 log(10) copies/mL in 23 (62%) of 37 patients at 12 months, 25 (78%) of 32 patients at 24 months, and 16 (84%) of 19 patients at 36 months. Except for one cirrhotic patient, serum alanine aminotransferase levels were below 50 IU/L in all patients during combination therapy. Serum creatinine levels increased in 14 (38%) of 37 patients, and serum phosphate levels decreased to below 2.5 mg/mL in 6 (16%) of 37 patients during combination therapy. Patients who received combination therapy for 36 months or longer had a significantly incidence of elevated serum creatinine levels. Fanconi syndrome occurred in a 57-year-old woman with cirrhosis after ADV was added to LAM. Combination therapy with ADV and LAM can maintain biochemical remission in patients with LAM-refractory HBV. However, the dosing interval of ADV should be adjusted according to renal function and serum phosphate levels in patients receiving long-term treatment.

Point mutation of ornithine decarboxylase gene in human hepatocellular carcinoma.

Ornithine decarboxylase (ODC) plays an important role in cell growth, and its activity is regulated by many mechanisms. The biochemical characteristics of ODC in malignant cells differ from those of ODC in normal cells. To determine whether novel changes occur in ODC in neoplastic tissue, we compared the nucleotide sequence of ODC cDNA obtained from human hepatoma tissue as determined by reverse transcriptase-PCR with that of ODC cDNA obtained from nontumorous tissue in the same patients. There were three point mutations accompanied by replacements of amino acids in hepatoma tissue with other amino acids or a stop codon. In one poorly differentiated hepatoma, codon 415, CAA was converted to TAA, resulting in replacement of Gln-415 by a stop codon. The mutated ODC protein produced by translation in a reticulocyte-lysate protein synthesizing system was truncated and stabilized in an ATP antizyme-dependent degradation system. These findings suggest that formation of a truncated and stabilized ODC protein due to point mutation is one reason why ODC activity is high in human hepatoma tissue.

Somatic mutation of mitochondrial DNA in cancerous and noncancerous liver tissue in individuals with hepatocellular carcinoma.

Unlike other types of cancer, hepatocellular carcinoma (HCC) is usually preceded by chronic inflammation caused by viral infection. The mutation of mitochondrial DNA (mtDNA) in hepatocarcinogenesis associated with viral infection was investigated. Compared with control liver tissue, the frequency of mtDNA mutations was markedly increased in both noncancerous and cancerous liver specimens from individuals with HCC. The accumulation of mtDNA mutations in HCC tissue reflected the degree of malignancy. The frequency of mtDNA mutations in HCC tissue was also greater than that described previously for other types of tumors. These observations suggest that the repeated destruction and regeneration of liver tissue associated with chronic viral hepatitis lead to the accumulation of mtDNA mutations. The genetic instability that results in the high rate of mtDNA mutation in cancerous liver tissue is also consistent with the multicentric hepatocarcinogenesis detected clinically.

Tumor-suppressor effect of interferon regulatory factor-1 in human hepatocellular carcinoma.

IFN regulatory factor-1 (IRF-1) regulates the IFN system, inhibits cell growth, and has tumor-suppressor activities. p21 is a universal cyclin-dependent kinase inhibitor, the induction of which depends on both p53 and IRF-1 in mouse embryonic fibroblasts. The expression of p21 in hepatocellular carcinomas (HCCs) is regulated by wild-type p53. We examined the expressions of IRF-1 and p21 in 32 HCCs by quantitative reverse transcription-PCR and the mutation p53 gene in 32 HCCs by single-strand conformation polymorphism and direct sequencing. The expression of IRF-1 mRNA in 15 of 32 HCCs was lower than that in adjacent noncancerous tissue. IRF-1 mRNA expression was reduced in 0 of 3 specimens of well-differentiated HCC, 9 of 21 (42%) specimens of moderately differentiated HCC, and 6 of 8 (75%) specimens of poorly differentiated HCC. IRF-1 mRNA expression was significantly lower in tumors with portal thrombus than in those without portal thrombus (P = 0.003). p53 mutations were detected in 7 of 32 HCCS: p21 expression was reduced in 6 of the 7 (86%) HCCs with p53 mutations. In contrast, p21 expression was reduced in 13 of 25 (52%) HCCs with wild-type p53. IRF-1 expression was reduced in 7 of 13 (53%) HCCs with both wild-type p53 and reduced expression of p21. These results suggest that IRF-1 may be a tumor-suppressor gene for HCC and that IRF-1 is related to p21 expression in HCC with wild-type p53.

Outcomes of dysplastic nodules in human cirrhotic liver: a clinicopathological study.

The number of dysplastic nodules detected clinically has increased since patients with hepatitis virus-associated cirrhosis, who are at increased risk for hepatocellular carcinoma (HCC), began to undergo regular cancer surveillance. Although it is potentially important to determine which type(s) of nodule may be prone to progress to HCC, outcomes of dysplastic nodules have not been fully investigated. This prompted us to examine the outcomes of dysplastic nodules in cirrhotic patients clinicopathologically. We studied 33 dysplastic nodules of <20 mm in maximum diameter, diagnosed by fine needle aspiration biopsy under ultrasonography (US). These nodules were clinically followed, mainly by US examination, for up to 70 months. When the nodules enlarged or exhibited changes on US, they were histologically reexamined by second biopsy. Surprisingly, 15 of the 33 nodules (45.5%) disappeared, 14 nodules (42.4%) remained unchanged, and only 4 nodules (12.1%) progressed to HCC. The latter 4 nodules were all hyperechoic on US and were composed of clear cells with fatty change or small cells with increased nuclear density, and in all 4 patients serum was positive for hepatitis C virus antibody. Univariate analyses revealed that, although not significant, the hyperechoic nodules or nodules with small cell change showed a higher HCC progression rate in comparison with the hypoechoic nodules or the nodules without small cell change. In summary, most of the dysplastic nodules we followed disappeared or remained unchanged, but some progressed to HCC. Hyperechoic nodules in patients with hepatitis C virus-associated cirrhosis, which show small cell change with increased nuclear density, may be prone to progress to HCC.

Effect of alcohol abuse on polyamine metabolism in hepatocellular carcinoma and noncancerous hepatic tissue.

BACKGROUND: Alcohol abuse is a risk factor for hepatocellular carcinoma (HCC) and the recurrence of HCC after resection. We therefore investigated polyamine metabolism, which is important in cell proliferation, HCC tissue, and noncancerous hepatic tissue. METHODS: In 30 patients who underwent liver resection for HCC, 13 patients had drunk 86 gm or more ethanol per day for at least 10 years (group 1), whereas the remaining 17 patients were nondrinkers or occasional drinkers (group 2). The control subjects were five patients who did not have liver disease or abuse alcohol. Tissue ornithine decarboxylase (ODC) activity and polyamine concentrations were measured. RESULTS: ODC activity in the HCC tissue was significantly higher in group 1 than in group 2. ODC activity in noncancerous tissue was significantly higher in group 1 than in group 2 and the control group. The ratio of spermidine/spermine in the HCC tissue was significantly higher in group 1 than in group 2. The ratio in noncancerous tissue was significantly higher in groups 1 and 2 than in the control group. CONCLUSIONS: Alcohol abuse affects polyamine metabolism, which influences the grade of malignancy of HCC. Hepatic tissue has greater potential for carcinogenesis in patients with chronic liver disease and alcohol abuse than in patients without them.

Does ascorbic acid prevent retinopathy during interferon therapy in patients with chronic hepatitis C?

PURPOSE: Ascorbic acid was administered to patients with chronic hepatitis C to elucidate the mechanism of onset of retinopathy during interferon (IFN) therapy, and its prevention. METHODS: The subjects were 62 patients with chronic hepatitis C who had been admitted to our hospital. For the IFN therapy, 6 MIU of natural IFN-alpha, or 10 MIU of recombinant human IFN-alpha 2b was administered every day for the first 2 weeks, followed by administration three times a week for 22 weeks. The patients were randomly assigned to a group receiving 600 mg/day of ascorbic acid or a group not receiving ascorbic acid (control group). The optic fundi were examined by ophthalmologists before the IFN therapy began and subsequently at weeks 2 and 4 and then every 4 weeks during the IFN therapy. RESULTS: Retinopathy was found in 9 of the 31 patients (29%) in the ascorbic acid-treated group and in 11 of the 31 patients (35%) in the control group. The cumulative incidence of hemorrhage in the ascorbic acid-treated group was lower than that in the control group during the IFN therapy, but the difference between the two groups was not significant (P = 0.186). The cumulative incidence of cotton-wool spots in the ascorbic acid-treated group was almost same as that in the control group during the IFN therapy. The median platelet counts before the therapy was begun were 11.8 x 10(4)/mm2 in the group with hemorrhage and 16.6 x 10(4)/mm2 in the group without, and the lowest platelet counts during IFN therapy were 7.3 x 10(4)/mm3 in the group with hemorrhage and 9.5 x 10(4)/mm3 in the group without, indicating significantly lower values in the group with hemorrhage (P = 0.018 and P = 0.020, respectively). The lowest platelet counts during IFN therapy were 7.4 x 10(4)/mm3 in the group with cotton-wool spots and 9.7 x 10(4)/mm3 in the group without, indicating a significantly lower value in the group with cotton-wool spots (P = 0.036). CONCLUSIONS: Ascorbic acid was not considered to be useful for the prevention of the retinopathy associated with IFN therapy in patients with chronic hepatitis C.

Relationship of polyamine metabolism to degree of malignancy of human hepatocellular carcinoma.

We investigated polyamine metabolism in hepatocellular carcinoma (HCC) with respect to tumor volume doubling time, degree of differentiation, and prevalence of portal invasion and intrahepatic metastasis. Ornithine decarboxylase (ODC) activity and the spermidine/spermine ratio were correlated with tumor volume doubling time. ODC activity was higher in moderately and poorly differentiated HCC than in well-differentiated HCC. The prevalence of portal invasion and intrehapatic metastasis was higher in patients with high ODC activities. We conclude that polyamine metabolism in HCC estimates the degree of malignancy.

Identification of genes differentially expressed by putrescine in HepG2 hepatoblastoma cells.

In order to identify genes differentially expressed by putrescine, a polyamine, which play important roles in the regulation of cell proliferation and the development of cancer, we performed mRNA differential display analysis using total RNA extracted from HepG2 cells (human hepatoblastoma cell line) treated with a specific inhibitor of polyamine biosynthesis, alpha-difluorometylornithine (DFMO). A total of 25 genes were up-regulated and 32 genes down-regulated by putrescine. Of the genes differentially expressed by putrescine, we chose three that were related to the respiratory chain and oxidative phosphorylation and analyzed them by Northern blot analysis. Cytochrome oxidase subunit 1, low molecular mass ubiquinone-binding protein, and NADH dehydrogenase subunit 2 were found to be down-regulated by putrescine. We examined intracellular ATP level in HepG2 cells, and found that ATP level in DFMO-treated cells was increased by exogenous putrescine.

Assessment of hepatic blood flow by PET with 15O water: correlation between per-rectal portal scintigraphy with 99Tc(m)-pertechnetate and scintigraphy with 99Tc(m)-GSA.

We performed positron emission tomography with 15O water (H2(15)O) to measure hepatic arterial and portal blood flow. In addition, portal haemodynamics and hepatic functional reserve were measured by per-rectal portal scintigraphy and scintigraphy with galactosyl human serum albumin, respectively. We studied 15 patients who had cirrhosis of the liver with underlying viral infection. After the intravenous injection of H2(15)O, positron emission tomography was performed. Blood samples were obtained after beginning the emission scan. The blood samples and positron emission tomographic images were analysed to calculate the radioactivity in the blood and liver. One-compartment model analysis was used to estimate hepatic arterial and portal blood flow. Computer acquisition of gamma-camera data was started just before the injection of 99Tc(m)-galactosyl human serum albumin. A receptor index and an index of blood clearance were calculated on the basis of the radioactivity of the liver and heart. A 99Tc(m)-pertechnetate solution was instilled into the rectum; serial scintigrams were performed and radioactivity curves for the liver and heart were recorded sequentially. A per-rectal portal shunt index was calculated from the curves. Median portal blood flow was 80 ml x 100 g(-1) x min(-1), median hepatic arterial blood flow was 56 ml x 100 g(-1) x min(-1), and median total hepatic blood flow was 138 ml x 100 g(-1) x min(-1) in patients with cirrhosis. The correlations between portal blood flow and the Child-Turcotte classification score, portal shunt index and receptor index were all significant. Our results show that hepatic arterial and portal blood flow can be measured by positron emission tomography with H2(15)O non-invasively and physiologically. This technique may be useful in pathophysiological studies of liver disease.

Clinical evaluation of staging system for nasopharyngeal carcinoma: comparison of fourth and fifth editions of UICC TNM classification.

Staging nasopharyngeal carcinoma (NPC) by the UICC 4th-edition TNM classification system (the old system) did not give an accurate prognosis because of the uneven distribution of patients in each stage. This system was revised in 1997 (the new system). To evaluate the performance of the new system, 35 patients with NPC who had been staged by the old system were restaged according to the new system. Restaging of the patients resulted in an overall "downstaging." Differences in the overall survival rates of the early group (stages I, II, III), stage IVA, stage IVB, and stage IVC patients were statistically significant (75%, 48%, 74%, and 0%. respectively; p = .01). T4 was a significant factor of poor outcome (hazard rate, 2.932; 95% CI, 1.667 to 8.545), whereas N3 was not (hazard rate, 0.858; 95% CI, 0.281 to 2.618). The new staging system is more useful than the old system.

Ornithine decarboxylase activity in the non-cancerous hepatic tissue of patients with hepatocellular carcinoma.

BACKGROUND/AIMS: Hepatocellular carcinoma may develop in patients with chronic hepatitis and cirrhosis. Active hepatitis is an important etiologic factor in the development of hepatocellular carcinoma. We measured ornithine decarboxylase activity, an important enzyme during cell proliferation, in non-cancerous hepatic tissue in patients with hepatocellular carcinoma. METHODOLOGY: Thirty-four patients who underwent liver resection for hepatocellular carcinoma were the subjects of this study. Hepatitis B surface antigen was detected in 7 patients (HBV group) and hepatitis C virus antibody was detected in 27 patients (HCV group). Tissue ornithine decarboxylase activity was measured. Histologic severity in active hepatitis (activity score) and degree of fibrosis (staging score) were determined. RESULTS: Ornithine decarboxylase activity was significantly higher in the HCV group than in the HBV and control groups. In all patients, ornithine decarboxylase activity correlated directly with the histologic activity score and the histologic staging score. In the HCV group, ornithine decarboxylase activity correlated with the histologic activity score. CONCLUSIONS: Ornithine decarboxylase activity in non-cancerous hepatic tissue correlated with the severity of active hepatitis and degree of fibrosis. In patients with hepatitis C virus, active hepatitis with increased ornithine decarboxylase activity is an important factor in the development of hepatocellular carcinoma.

Resected cases of hepatocellular carcinoma detected after interferon therapy for chronic hepatitis C.

BACKGROUND/AIMS: Interferon therapy decreases the incidence of hepatocellular carcinoma in patients infected with hepatitis C virus. However, hepatocellular carcinoma was detected after interferon therapy in some patients. METHODOLOGY: Of the 167 patients who underwent liver resection for hepatitis C virus-related hepatocellular carcinoma between 1993 and September 1998, the carcinoma was detected after interferon therapy in 11 patients. The clinicopathologic findings in these 11 patients were studied. RESULTS: The response to interferon was complete (n = 4), partial (n = 4), or no response (n = 3). Hepatocellular carcinoma was detected 2 months to 3 years 9 months, after interferon therapy. The interval period from the end of interferon therapy to the detection of the carcinoma were significantly correlated with the longest diameter of the main tumor (P = 0.0043), indicating that most carcinomas have already developed before the end of interferon therapy. In one non-responder, multicentric carcinogenesis occurred after liver resection for primary hepatocellular carcinoma. Another patient with advanced hepatocellular carcinoma died of the recurrence. CONCLUSIONS: Surveillance for hepatocellular carcinoma must be performed even in patients successfully treated with interferon because occult carcinoma may have developed before or during the therapy.

Case of small hepatocellular carcinoma in the caudate lobe detected after interferon caused disappearance of hepatitis C virus.

The high prevalence of antibodies to hepatitis C virus (HCV) in patients with hepatocellular carcinoma (HCC) in Japan suggests that the virus has a close relationship to hepatocarcinogenesis (1-4). HCV causes chronic inflammation of the human liver and HCC may finally develop, by way of an unknown mechanism. Interferon (IFN), which has an antiviral effect, is widely used for treatment of chronic hepatitis C infection (5). In Japan, about 40% of such patients have been cured of the infection by IFN therapy (6). The most suitable criteria for identification of a complete response to IFN are the most rigorous: both the disappearance of HCV RNA, verified by the polymerase chain reaction (PCR), and alanine aminotransferase activity in the normal range for at least six months after the end of the therapy. In the cured patients, the liver disorder and hepatocarcinogenesis are thought to stop progressing. However, few such patients have been monitored for years following the treatment (7-8). In this article, we describe a patient with small HCC in the caudate lobe after complete response to IFN therapy for chronic hepatitis. We suggest the necessity for regular liver checks for patients from whom HCV is eliminated by IFN therapy.

High prevalence of infection with hepatitis B and C viruses in patients with hepatocellular carcinoma in Japan.

BACKGROUND/AIMS: Hepatitis B and C viruses are closely associated with hepatocellular carcinoma. We studied the prevalence of infection with either virus in patients with this cancer by examination of sera and tumor tissue. METHODOLOGY: Serum samples obtained before treatment from 330 patients with hepatocellular carcinoma were assayed for antibodies against hepatitis C virus and against hepatitis B surface and core antigen. Tumor tissues from 65 patients were examined for hepatitis B virus RNA. RESULTS: Of the 330 patients, 87 had anti-hepatitis C alone; 161 had anti-hepatitis C and anti-hepatitis B (core); 13 had anti-hepatitis C and anti-hepatitis B (surface); 39 had anti-hepatitis B (surface) alone; and, 19 had anti-hepatitis B (core) alone. Eleven patients had none of these. Hepatitis B virus genes were detected in tumor tissue in all 13 patients with anti-surface antibody, in 21 of 30 patients with anti-core antibody, and in 9 of 22 patients without hepatitis B antibodies. Viral genes were detected in tumor tissue in 5 of 11 patients with neither B nor C virus markers in their sera; viral markers were found in either serum or tumor tissue in 324 of 330 patients (98.2%). CONCLUSIONS: The prevalence of hepatitis B or C virus infection in patients with hepatocellular carcinoma in Japan is extremely high. The prevalence of co-infection with both viruses is also high.

Relationship between ornithine decarboxylase gene abnormalities and human hepatocarcinogenesis.

BACKGROUND/AIMS: Ornithine decarboxylase is essential for cell growth. Its activity was high in human hepatocellular carcinoma tissues and was highest in poorly differentiated tumors. METHODOLOGY: To find if there are tumor-specific ornithine decarboxylases, we examined the ornithine decarboxylase cDNA sequences of 91 clones prepared from hepatoma tissue and non-cancerous tissue of resected liver specimens from 15 patients with hepatocellular carcinoma. RESULTS: Ornithine decarboxylase gene mutations were more frequently detected in the hepatoma tissue. The incidence of mutation in hepatoma tissue was related to dedifferentiation. Mutation in regions rich in proline, glutamic acid, serine, and threonine were detected in moderately and poorly differentiated hepatocellular carcinoma only. CONCLUSIONS: Our findings suggested that the sequence of ornithine decarboxylase in hepatocellular carcinoma often is different from that in normal liver and that mutation of its gene is related to the progression of hepatocellular carcinoma.