Liver iron excess in patients with hepatocellular carcinoma developed on non-alcoholic steato-hepatitis

Iron metabolism in Nonalcoholic Fatty Liver Disease

Non-Alcoholic Fatty Liver Disease (NAFLD) is a common worldwide clinical and major public health problem affecting both adults and children in developed nations. Increased hepatic iron stores are observed in about one-third of adult NAFLD patients. Iron deposition may occur in parenchymal and/or non-parenchymal cells of the reticuloendothelial system (RES). Similar patterns of iron deposition have been associated with increased severity of other chronic liver diseases including HCV infection and dysmetabolic iron overload, suggesting there may be a common mechanism for hepatic iron deposition in these diseases. In NAFLD, iron may potentiate the onset and progression of disease by increasing oxidative stress and altering insulin signaling and lipid metabolism. The impact of iron in these processes may depend upon the sub-cellular location of iron deposition in hepatocytes or RES cells. Iron depletion therapy has shown efficacy at reducing serum aminotransferase levels and improving insulin sensitivity in subjects with NAFLD.

Iron and steatohepatitis

As the main iron storage site in the body and the main source of the iron-regulatory hormone, hepcidin, the liver plays a pivotal role in iron homeostasis. A variable degree of hepatic iron accumulation has long been recognized in a number of chronic liver diseases. Both alcoholic and non-alcoholic steatohepatitis display increased iron deposits in the liver, with an hepatocellular, mesenchymal, or mixed pattern, and recent reports have documented a concomitant aberrant hepcidin expression that could be linked to different coincidental pathogenic events (e.g. the etiological agent itself, necroinflammation, metabolic derangements, genetic predisposition). The present study reviews the pathogenic mechanisms of iron accumulation in steatohepatitis during alcoholic and non-alcoholic liver disease and the role of excess iron in chronic disease progression.

Clinical features of nonalcoholic fatty liver disease-associated hepatocellular carcinoma

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD), especially nonalcoholic steatohepatitis, is a recognized risk factor for hepatocellular carcinoma (HCC). However, detailed analysis of the clinical features in patients with NAFLD and their association with HCC is lacking. This study aimed to update the clinical features of patients with NAFLD-associated HCC.

DATA SOURCES

The clinical data of patients with NAFLD-associated HCC from 25 studies published between 1990 and 2010 in the Pubmed database were comprehensively reviewed.

RESULTS

In a total of 169 patients with NAFLD-associated HCC, 72.8% were male. The median age at abnormal liver function tests and diagnosis of NAFLD and HCC was 60, 64 and 67 years, respectively. Most patients were obese (75%) and diabetic (59.8%), 32.3% had dyslipidemia, and 53% had hypertension. Nearly all patients (98.6%, 71/72) were complicated with at least one metabolic disorder. The majority (76%) of the HCC patients had a solitary tumor nodule, with the tumor size ranging from 0.8 to 20 cm in diameter (mean 3.4 cm). Most (61.1%) of the patients had moderately-differentiated HCC. In 40.2% of the patients, HCC occurred in the absence of cirrhosis. Among 130 patients, 57.7% underwent hepatectomy and 14.6% received liver transplantation. The mean follow-up of the treated patients for 25 months showed that 32.4% (24/74) died and 18.8% (9/48) had recurrence.

CONCLUSIONS

Patients with NAFLD-associated HCC are usually accompanied with metabolic disorders. Regular surveillance in patients with NAFLD for HCC is necessary, especially for elderly men with metabolic syndrome.

Hepatocellular carcinoma in non-alcoholic steatohepatitis: Growing evidence of an epidemic?

The incidence of hepatocellular carcinoma in non-viral-related chronic liver disease has gradually increased in Japan. Obesity and diabetes mellitus type 2 have been established as a significant risk factor for hepatocellular carcinoma (HCC) by epidemiologic observations and experimental studies. The risks of these factors for HCC are likely conferred by two factors: the increased risk for development of non-alcoholic steatohepatitis (NASH) and the carcinogenic potential of themselves. Hepatocellular carcinoma in NASH is difficult to evaluate because histological diagnosis is required for diagnosis of NASH, which can lead selection bias. Furthermore, end-stage NASH is in effect "burned-out" NASH, for which the diagnosis of NASH cannot be made any more. At all events, previous studies on the etiology of Japanese HCC showed that non-alcoholic fatty liver disease accounts for 1-5% of all HCC (male predominant, median age 72 years). They have high prevalences of obesity and/or diabetes mellitus type 2 and 10-75% of the HCC arose from non-cirrhotic livers. HCC in NASH may be of multicentric origin, similar to HCC based on viral hepatitis. Regular screening for HCC is extremely important especially in cirrhotic NASH patients and recurrence should be warned. In western and Asian countries, the prevalence of non-alcoholic fatty liver disease in the general population is increasing dramatically. Therefore, there is an urgent need to elucidate pathogenesis and clinical features of HCC in NASH. In this review we summarize current concepts for HCC in NASH.

Iron overload in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a major causative agent of chronic liver disease worldwide, but the actual mechanisms responsible for liver injury remain unclear. NAFLD includes a spectrum of clinical entities ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) with possible evolution to cirrhosis and hepatocellular carcinoma. Iron is considered a putative element that interacts with oxygen radicals in inducing liver damage/fibrosis and insulin resistance. The role of hepatic iron in the progression of NASH remains controversial, but in some patients, iron may have a role in the pathogenesis of NASH. Though genetic factors, insulin resistance, dysregulation of iron-regulatory molecules, erythrophagocytosis by Kupffer cells may be responsible for hepatic iron accumulation in NASH, exact mechanisms involved in iron overload remain to be clarified. Iron reduction therapy such as phlebotomy or iron-restricted diet may be promising in patients with NAFLD/NASH to reduce hepatic injury as well as insulin resistance. Larger controlled trials of longer duration are warranted to assess the long-term clinical benefit of phlebotomy and/or iron-restricted diet in NAFLD/NASH.

Type 2 diabetes and hepatocellular carcinoma: a case-control study in patients with chronic hepatitis B

Type 2 diabetes has been suggested as an independent risk factor for the development of hepatocellular carcinoma (HCC). However, the role of Type 2 diabetes on the development of HCC in the presence of chronic hepatitis B (CHB) remains inconclusive. We conducted this hospital-based case-control study to evaluate the roles of Type 2 diabetes in HCC development in patients with CHB. From January 2004 to December 2008, a total of 6,275 eligible consecutive patients with chronic hepatitis B virus (HBV) infection were recruited. A total of 1,105 of them were patients with HBV-related HCC and 5,170 patients were CHB but without HCC. We used multivariate logistic regression models to investigate the association between Type 2 diabetes and HCC risk. The prevalence of Type 2 diabetes is higher among HCC patients without cirrhosis than among those with cirrhosis (12.1% vs. 6.7%, p=0.003). Type 2 diabetes was associated with a significantly high risk of HCC in female patients after adjusting for age, family history of HCC, city of residence, hepatitis B e antigen and cirrhosis with an odds ratio (95% confidence interval, CI) of 1.9 (1.1-3.4). Restricted analyses among female patients without cirrhosis indicated that Type 2 diabetes was strongly associated with HCC risk with adjusted odds ratio (95% CI) of 5.6 (2.2-14.1). In conclusion, Type 2 diabetes is independently associated with the increased risk of HCC in female CHB patients. Female CHB patients with Type 2 diabetes are of a high HCC risk population and should be considered for HCC close surveillance program.

Biochemical and histological liver changes occurred after iron supplementation and possible remediation by garlic consumption

Iron liver excess is associated to biochemical and histological liver perturbations. Our aim was to know even if fresh garlic consumption can remediate these problems. Three groups of rats were utilized: control group A, iron overload group B and garlic and iron overload group C. Important morphological and biochemical modifications were obtained in group B rats comparatively to control group A. Indeed, body and liver weights and liver iron contents increased, respectively, by 12.5 ± 0.06%; 17 ± 0.25% and 35 ± 0.11% comparatively to controls. Radical cation scavenging ability in liver cytosol of group B rats was significantly low (54 ± 0,1%) in comparison to group A. Garlic consumption allowed the group C to achieve an increase by 46 ± 0,11 and 75 ± 0,14% of total antioxidant capacity comparatively to group A and B rats. For the serum ALAT, ASAT, triglyceride and LDH levels, they increased in iron-treated rats, respectively, by 25 ± 0.21; 15 ± 0.12; 30 ± 0.14 and 22 ± 0.16% comparatively to controls. These perturbations were accompanied by deep histological changes. After food fresh garlic supplementation, we had found a deep regulation of all modified parameters showing a hepatoprotective effect of garlic against iron liver excess. Garlic chemical compounds have curative effects on iron liver excess.

Downregulation of hemojuvelin prevents inhibitory effects of bone morphogenetic proteins on iron metabolism in hepatocellular carcinoma

Recently, we revealed that bone morphogenetic protein (BMP) 4 is increased in hepatocellular carcinoma (HCC). Furthermore, latest reports described BMPs, in particular BMP6, as important regulators of hepcidin expression in iron homeostasis. Therefore, we aimed to unravel why enhanced BMP expression in HCC patients does not lead to severe changes in iron metabolism. Initial analysis of the BMP4 and BMP6 expression patterns revealed enhanced expression on mRNA and protein level in HCC cell lines and tissue samples compared with primary human hepatocytes (PHHs) and normal liver tissues. However and interestingly, hepcidin expression was reduced in HCC cell lines and tissues. Analysis of BMP6 receptor expression revealed loss of BMP6-specific receptor subunit in HCC. To identify a possible regulatory mechanism causing lack of reaction to BMP4 we analyzed the expression of hemojuvelin (HJV), which is involved in iron metabolism as BMP co-receptor. HJV expression was markedly decreased in HCC cell lines and tissues. HJV promoter analysis revealed potential HNF-1α and snail-binding sites, but functional analysis ruled out that these transcriptional regulators or promoter methylation are the cause of HJV downregulation in HCC. However, we identified AU-rich elements in the HJV 3'-untranslated region and revealed significantly faster decay of HJV mRNA in HCC cells as compared with PHH indicating decreased mRNA-stability as the reason for the loss of HJV expression in HCC.

Iron in fatty liver and in the metabolic syndrome: a promising therapeutic target

The dysmetabolic iron overload syndrome (DIOS) is now a frequent finding in the general population, as is detected in about one third of patients with nonalcoholic fatty liver disease (NAFLD) and the metabolic syndrome. The pathogenesis is related to altered regulation of iron transport associated with steatosis, insulin resistance, and subclinical inflammation, often in the presence of predisposing genetic factors. Evidence is accumulating that excessive body iron plays a causal role in insulin resistance through still undefined mechanisms that probably involve a reduced ability to burn carbohydrates and altered function of adipose tissue. Furthermore, DIOS may facilitate the evolution to type 2 diabetes by altering beta-cell function, the progression of cardiovascular disease by contributing to the recruitment and activation of macrophages within arterial lesions, and the natural history of liver disease by inducing oxidative stress in hepatocytes, activation of hepatic stellate cells, and malignant transformation by promotion of cell growth and DNA damage. Based on these premises, the association among DIOS, metabolic syndrome, and NAFLD is being investigated as a new risk factor to predict the development of overt cardiovascular and hepatic diseases, and possibly hepatocellular carcinoma, but most importantly, represents also a treatable condition. Indeed, iron depletion, most frequently achieved by phlebotomy, has been shown to decrease metabolic alterations and liver enzymes in controlled studies in NAFLD. Additional studies are warranted to evaluate the potential of iron reductive therapy on hard clinical outcomes in patients with DIOS.

3,5,5-trimethyl-hexanoyl-ferrocene diet protects mice from moderate transient acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) overdose is the most frequent cause of adult acute liver failure. Susceptibility or resistance to APAP toxicity is most likely accounted for by the interplay of several factors. One factor important in multiple different chronic liver diseases that may play a role in APAP toxicity is elevated hepatic iron. Hereditary hemochromatosis is traditionally associated with hepatic iron overload. However, varying degrees of elevated hepatic iron stores observed in chronic hepatitis C and B, alcoholic liver disease and nonalcoholic fatty liver disease also have clinical relevance. We employed an animal model in which mice are fed a 3,5,5-trimethyl-hexanoyl-ferrocene (TMHF)-supplemented diet to evaluate the effect of elevated hepatic iron on APAP hepatotoxicity. Three hundred milligrams per kilogram APAP was chosen because this dosage induces hepatotoxicity but is not lethal. Since both excess iron and APAP induce oxidative stress and mitochondrial dysfunction, we hypothesized that the TMHF diet would enhance APAP hepatotoxicity. The results were the opposite. Centrilobular vacuolation/necrosis, APAP adducts, nitrotyrosine adducts, and a spike in serum alanine aminotransferase, which were observed in control mice treated with APAP, were not observed in TMHF-fed mice treated with APAP. Further analysis showed that the levels of CYP2E1 and CYP1A2 were not significantly different in TMHF-treated compared with control mice. However, the magnitude of depletion of glutathione following APAP treatment was considerably less in TMHF-treated mice than in mice fed a control diet. We conclude that a TMHF diet protects mice from moderate transient APAP-induced hepatotoxicity prior to the formation of APAP adducts, and one contributing mechanism is reduction in glutathione depletion.

The FBXL5-IRP2 axis is integral to control of iron metabolism in vivo

Iron-dependent degradation of iron-regulatory protein 2 (IRP2) is a key event for maintenance of an appropriate intracellular concentration of iron. Although FBXL5 (F box and leucine-rich repeat protein 5) is thought to mediate this degradation, the role of FBXL5 in the control of iron homeostasis in vivo has been poorly understood. We have now found that mice deficient in FBXL5 died in utero, associated with excessive iron accumulation. This embryonic mortality was prevented by additional ablation of IRP2, suggesting that impaired IRP2 degradation is primarily responsible for the death of Fbxl5(-)(/-) mice. We also found that liver-specific deletion of Fbxl5 resulted in deregulation of both hepatic and systemic iron homeostasis, leading to the development of steatohepatitis. The liver-specific mutant mice died with acute liver failure when fed a high-iron diet. Thus, our results uncover a major role for FBXL5 in ensuring an appropriate supply of iron to cells.

Non-alcoholic fatty liver disease: is iron relevant?

Non-alcoholic fatty liver disease (NAFLD) is a common and ubiquitous disorder (Bedogni et al. in Hepatology 42:44-52, 2005; Bellentani et al. in Ann Intern Med 132:112-117, 2000) which in a proportion of subjects leads to non-alcoholic steatohepatitis (NASH), advanced liver disease and hepatocellular carcinoma. Although the factors responsible for progression of disease are still uncertain, there is evidence that insulin resistance (IR) is a key operative mechanism (Angulo et al. in Hepatology 30:1356-1362, 1999) and that two stages are involved. The first is the accumulation of triglycerides in hepatocytes followed by a "second hit" which promotes cellular oxidative stress. Several factors may be responsible for the induction of oxidative stress but hepatic iron has been implicated in various studies. The topic is controversial, however, with early studies showing an association between hepatic iron (with or without hemochromatosis gene mutations) and the progression to hepatic fibrosis. Subsequent studies, however, could not confirm an association between the presence of hepatic iron and any of the histological determinants of NAFLD or NASH. Recent studies have reactivated interest in this subject firstly, with the demonstration that hepatic iron loading increases liver cholesterol synthesis with increased lipid deposition in the liver increasing the cellular lipid burden and secondly, a large clinical study has concluded that hepatocellular iron deposition is associated with an increased risk of hepatic fibrosis, thus, strongly supporting the original observation made over a decade ago. An improvement in insulin sensitivity has been demonstrated following phlebotomy therapy but a suitably powered controlled clinical trial is required before this treatment can be implemented.

Combination treatment of angiotensin II type I receptor blocker and new oral iron chelator attenuates progression of nonalcoholic steatohepatitis in rats

Angiotensin II type I receptor blocker and iron chelator reportedly exert suppressive effects on nonalcoholic steatohepatitis (NASH) progression, including liver fibrosis and hepatocarcinogenesis. The aim of this study was to elucidate the combined effect of losartan (LOS), an angiotensin II type I receptor blocker, and deferasirox (DSX), a newly developed oral iron chelator, on the progression of NASH in rats. To induce NASH, F344 rats were fed a choline-deficient l-amino acid-defined diet for 12 wk, and the effects of LOS and DSX at clinically comparable low doses were elucidated in conjunction with oxidative stress, neovascularization, and hepatic stellate cells (HSC) activation, all known to play important roles in the progression of NASH. Treatment with both LOS and DSX suppressed choline-deficient L-amino acid-defined diet-induced liver fibrosis development and hepatocarcinogenesis. This combination treatment exerted a stronger inhibitory effect compared with treatment with a single agent. These inhibitory effects occurred almost concurrently with the suppression of oxidative stress, neovascularization, and HSC activation. Our in vitro study demonstrated that LOS and DSX inhibited angiotensin II-induced proliferation, transforming growth factor-β(1) expression of activated HSC, and in vitro angiogenesis. These results indicated that dual inhibition by combined treatment of LOS and DSX attenuated the progression of NASH. Since both agents are widely used in clinical practice, this combination therapy may represent a potential new strategy against NASH in the near future.

Beyond hereditary hemochromatosis: new insights into the relationship between iron overload and chronic liver diseases

Following the model of hereditary hemochromatosis, the possible role of iron overload as a cofactor for disease progression in acquired liver diseases has been investigated with controversial results. In recent years, progress has been made in understanding the regulation of iron metabolism, thereby allowing the evaluation of the mechanisms linking liver diseases to excessive iron accumulation. Indeed, deregulation of the transcription of hepcidin, emerging as the master regulator of systemic iron metabolism, has been implicated in the pathogenesis of hepatic iron overload in chronic liver diseases. Whatever the cause, hepatocellular iron deposition promotes liver fibrogenesis, while an emerging possible aggravating factor is represented by the strong link between iron stores and insulin resistance, a recently recognized risk factor for the progression of liver diseases. Overall, these pathogenic mechanisms, together with the known proliferative and mutagenic effect of excess iron, converge in determining an increased susceptibility to hepatocellular carcinoma. Finally, an association between serum ferritin levels and mortality in patients with end-stage liver disease has recently been reported. Prospective, randomized studies are required to evaluate whether iron depletion may reduce fibrosis progression, hepatocellular carcinoma development, and eventually mortality in patients with chronic liver diseases.

Relationship between the pattern of hepatic iron deposition and histological severity in nonalcoholic fatty liver disease

Previous studies examining the relationship between hepatic iron deposition and histological severity in nonalcoholic fatty liver disease (NAFLD) have been inconclusive. The goal of this study was to examine the relationship between hepatic iron deposition and liver histology in 849 patients enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network. Hepatic iron staining was performed in a central laboratory, and the stains were scored for grade and cellular and parenchymal localization by a central pathology committee; the relationship between the grade and pattern of iron deposition and the clinical, laboratory, and histological variables was examined with univariate and multivariate analyses. Stainable hepatic iron was present in 293 of 849 patients (34.5%) in one of three histological patterns: a hepatocellular (HC) pattern [63/849 (7.4%)], a reticuloendothelial system (RES) cell pattern [91/849 (10.7%)], or a mixed RES/HC pattern [139/849 (16.4%)]. Patients with the RES iron-staining pattern were more likely to have advanced fibrosis compared to those with those with HC iron (P = 0.01). Patients with RES iron were also more likely to have advanced histological features such as fibrosis (P = 0.049), portal inflammation (P = 0.002), HC ballooning (P = 0.006), and definite nonalcoholic steatohepatitis (P = 0.007) compared to those with patients with HC or mixed iron patterns. The presence of RES iron (odds ratio = 1.60, 95% confidence interval = 1.10-2.33, P = 0.015) was independently associated with advanced hepatic fibrosis on multiple regression analysis after adjustments for age, gender, diabetes status, and body mass index.

CONCLUSION

The presence and pattern of hepatic iron deposition are associated with distinct histological features in patients with NAFLD and may have implications for pathophysiology and therapy.

Hepatocellular carcinoma in non-cirrhotic liver: a reappraisal

Although not frequently, hepatocellular carcinoma (HCC) can ensue in a non-cirrhotic liver. As compared to cirrhotic HCC, this kind of tumour has some peculiarities, such as: (a) a lower male preponderance and a bimodal age distribution; (b) a lower prevalence of the three main risk factors (hepatitis B and C virus infections and alcohol abuse), with an increased prevalence of other etiologic factors, such as exposure to genotoxic substances and sex hormones, inherited diseases, genetic mutations; (c) a more advanced tumour stage at the time of diagnosis, as it is usually detected due to the occurrence of cancer-related symptoms, outside any scheduled surveillance program; (d) a much higher amenability to hepatic resection, due to the low risk of liver failure even after extended parenchymal mutilation; (e) overall and disease-free survivals after resection of non-advanced tumours (meeting the Milano criteria) comparable to that obtained with liver transplantation in cirrhotic patients carrying an early tumour; (f) overall survival strictly dependent on tumour burden (and its recurrence) and barely influenced by liver function.

Nonalcoholic fatty liver disease and hepatocellular carcinoma: a weighty connection

Hepatocellular carcinoma (HCC) is a common and deadly malignancy that is increasing in incidence in developed countries. The emergence of hepatitis C virus (HCV) accounts for about half of this increase in HCC, although the etiology of HCC in 15%-50% of new HCC cases remains unclear. The most common form of chronic liver disease in developed countries is nonalcoholic fatty liver disease (NAFLD), which encompasses a broad spectrum of histopathology. The prevalence of NAFLD, including the more aggressive nonalcoholic steatohepatitis (NASH), is increasing with the growing epidemics of diabetes and obesity. NASH can progress to cirrhosis and its related complications. Growing evidence suggests that NASH accounts for a large proportion of idiopathic or cryptogenic cirrhosis, which is associated with the typical risk factors for NASH. HCC is a rare, although important complication of NAFLD. Diabetes and obesity have been established as independent risk factors for the development of HCC. New evidence also suggests that hepatic iron deposition increases the risk of HCC in NASH-derived cirrhosis. Multiple case reports and case reviews of HCC in the setting of NASH support the associations of diabetes and obesity with the risk of HCC, as well as suggest age and advanced fibrosis as significant risks. Insulin resistance and its subsequent inflammatory cascade that is associated with the development of NASH appear to play a significant role in the carcinogenesis of HCC. The complications of NASH, including cirrhosis and HCC, are expected to increase with the growing epidemic of diabetes and obesity.

Biting the iron bullet: endoplasmic reticulum stress adds the pain of hepcidin to chronic liver disease

Hepcidin is a peptide hormone that is secreted by the liver and controls body iron homeostasis. Hepcidin overproduction causes anemia of inflammation, whereas its deficiency leads to hemochromatosis. Inflammation and iron are known extracellular stimuli for hepcidin expression. We found that endoplasmic reticulum (ER) stress also induces hepcidin expression and causes hypoferremia and spleen iron sequestration in mice. CREBH (cyclic AMP response element-binding protein H), an ER stress-activated transcription factor, binds to and transactivates the hepcidin promoter. Hepcidin induction in response to exogenously administered toxins or accumulation of unfolded protein in the ER is defective in CREBH knockout mice, indicating a role for CREBH in ER stress-regulated hepcidin expression. The regulation of hepcidin by ER stress links the intracellular response involved in protein quality control to innate immunity and iron homeostasis.

Metabolic syndrome and hepatocellular carcinoma: two growing epidemics with a potential link

Hepatocellular carcinoma (HCC) is the most rapidly increasing cause of cancer death in the United States. Although many risk factors for HCC are well defined, including hepatitis B virus (HBV), hepatitis C virus (HCV), and alcohol, most series have indicated that 5% to 30% of patients with HCC lack a readily identifiable risk factor for their cancer. The majority of "cryptogenic" HCC in the United States is attributed to nonalcoholic fatty liver disease (NAFLD), a hepatic manifestation of the metabolic syndrome. The metabolic syndrome is a constellation of problems that includes insulin resistance, obesity, hypertension, and hyperlipidemia. Increasingly, components of the metabolic syndrome are being linked to various forms of cancer with respect to both increased risk of disease and worsened outcome. In this review, the authors focused on the relation between metabolic syndrome and HCC. They investigated the increased risks of HCC among individuals with features of metabolic syndrome, potentially worsened cancer outcomes in these patients, possible pathogenic mechanisms to explain these relations, and treatment options for those with NAFLD and its progressive counterpart, nonalcoholic steatohepatitis. It is predicted that metabolic syndrome will lead to large increases in the incidence of HCC over the next decades. A better understanding of the relation between these 2 diseases ultimately should lead to improved screening and treatment options for patients with HCC.

Hepatic iron overload and risk of hepatocellular carcinoma in cirrhosis

Iron accumulation in the liver is considered to be a co-factor for progression of liver disease. Iron overload can enhance the effects of oxidative stress and influence the natural history of patients with cirrhosis, exposing them to a higher risk of hepatocellular carcinoma. The results of clinical studies designed to assess the impact of liver iron content on the risk of tumor development have remained controversial for some time. It is known that common factors can affect both liver iron overload and the risk of cancer, necessitating multivariate analyses of these features in large cohorts of cirrhotic patients. Furthermore, the causes and consequences of hepatic iron overload appear to depend on the cause of the underlying liver disease. Thus, the only solid evidence of a relationship between liver iron overload and event occurrence has come from longitudinal studies conducted in homogeneous cohorts of patients with cirrhosis. So far, the available data suggest that iron accumulation in the liver is an independent risk factor for hepatocellular carcinoma in patients with alcoholic cirrhosis and/or nonalcoholic hepatosteatosis, but not in those with viral hepatitis C cirrhosis.

The global burden of iron overload

There have been major developments in the field of iron metabolism in the past decade following the identification of the HFE gene and the mutation responsible for the C282Y substitution in the HFE protein. While HFE-associated hemochromatosis occurs predominantly in people of northern European extraction, other less-common mutations can lead to the same clinical syndrome and these may occur in other populations in the Asian-Pacific region. The most common of these is the mutation that leads to changes in the ferroportin molecule, the protein responsible for the transport of iron across the basolateral membrane of the enterocyte and from macrophages. Recent research has unraveled the molecular processes of iron transport and regulation of how these are disturbed in hemochromatosis and other iron-loading disorders. At the same time, at least one new oral iron chelating agent has been developed that shows promise in the therapy of hemochromatosis as well as thalassemia and other secondary causes of iron overload. It is pertinent therefore to examine the developments in the global field of iron overload that have provided insights into the pathogenesis, disease penetrance, comorbid factors, and management.