Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and the third leading cause of cancer-related mortality worldwide, responsible for approximately 750,000 deaths annually. It develops almost exclusively in the setting of chronic liver disease, with >90% of cases arising in cirrhotic livers, representing the natural evolution of progressive hepatic fibrosis. The incidence varies dramatically by geography, with highest rates in East Asia and sub-Saharan Africa due to endemic hepatitis B infection, while in Western countries hepatitis C and alcoholic cirrhosis predominate. Early detection through surveillance of at-risk populations and understanding of its pathophysiology are critical for improving outcomes, as survival is highly dependent on stage at diagnosis and liver function reserve. HCC represents a frequent board topic because it integrates knowledge of chronic liver disease, oncologic principles, and multimodal therapeutic decision-making. Understanding HCC is essential for internal medicine and subspecialty practice, as nearly all patients with cirrhosis require surveillance and risk stratification.

The development of HCC is fundamentally rooted in the progressive accumulation of genetic and epigenetic alterations within hepatocytes subjected to chronic inflammatory, oxidative, and fibrotic stress. The carcinogenic process typically unfolds through a stepwise progression: chronic hepatic injury → inflammation → fibrosis → cirrhosis → dysplasia → HCC, though this sequence may be variable.

Persistent hepatic inflammation from viral hepatitis, alcohol, or metabolic disease generates reactive oxygen species (ROS) that damage hepatocyte DNA and telomeres. Cytokine signaling (particularly IL-6, TNF-α) and sustained hepatocyte necrosis trigger compensatory proliferation and regeneration. This chronic proliferative state substantially increases the risk of mutagenic events. Additionally, inflammatory cells infiltrating cirrhotic liver produce cytokines that activate hepatic stellate cells, perpetuating the fibrotic response and creating a pro-carcinogenic microenvironment with altered growth factor signaling and angiogenesis.

The development of cirrhosis fundamentally alters hepatic architecture, creating nodules of regenerating hepatocytes surrounded by fibrous septa. This microvascular distortion increases shear stress and hypoxia within nodules, favoring dysplastic transformation. The dysplastic nodule (early or advanced) represents the precancerous lesion and is characterized by increased cellularity, increased nuclear-to-cytoplasmic ratio, and hyperchromatic nuclei, but lacks convincing vascular invasion. The transition from dysplastic nodule to HCC is marked by acquisition of an arterial blood supply (angiogenesis driven by VEGF and hypoxia), enabling rapid growth and heterogeneous enhancement on imaging.

Multiple pathways drive hepatocarcinogenesis with variable frequency depending on underlying etiology. The TP53 tumor suppressor is inactivated in 20-50% of HCCs, particularly in hepatitis B-related cases and advanced tumors. The CTNNB1 gene (encoding β-catenin) is activated in 15-40% of cases, promoting Wnt/β-catenin pathway signaling and generally associated with better differentiation but worse prognosis paradoxically. AXIN1 and APC mutations also dysregulate Wnt signaling. The RB pathway is disrupted through CDKN2A/p16 loss or cyclin E1 amplification in approximately 25-50% of cases. More recently, mutations in chromatin remodeling genes (ARID1A, BAP1) and DNA damage response genes have been identified. TERT promoter mutations occur in 50-70% of HCCs and are among the earliest clonal events, conferring unlimited replicative potential. Hepatitis B virus integration into the genome directly disrupts genes and produces oncogenic viral proteins (HBsAg, HBx), while hepatitis C virus-encoded proteins (NS5A, NS5B) inhibit apoptosis and promote fibrosis. These molecular events progressively dysregulate growth-inhibitory pathways, enhance survival signaling, and promote epithelial-to-mesenchymal transition.

As HCC nodules exceed 1-2 mm, diffusion becomes inadequate and hypoxia activates HIF-1α, driving VEGF and other angiogenic factor production. This neovascularization from hepatic arterial sources (rather than portal venous) is the hallmark radiologic feature and enables rapid growth. Angiopoietin dysregulation and loss of contact inhibition further promote aberrant vascular development.

HCC develops within a profoundly immunosuppressed hepatic microenvironment characterized by increased regulatory T cells, myeloid-derived suppressor cells, and exhausted T cells expressing PD-1 and TIM-3. Tumor cells upregulate PD-L1, down-regulate MHC expression, and produce immunosuppressive cytokines (IL-10, TGF-β), facilitating escape from immune surveillance despite chronic underlying inflammation.

HBV is the single most common etiologic agent globally, responsible for 50-55% of all HCC cases, particularly in East Asia and Africa. HCC can develop in patients with chronic HBV even without cirrhosis, though cirrhosis greatly accelerates risk. The mechanisms include direct viral oncogenicity (HBx protein inactivates p53 and promotes genomic instability), chronic immune-mediated hepatocyte destruction, and HBV DNA integration into the hepatocyte genome causing insertional mutagenesis. High viral loads and HBeAg positivity are associated with increased HCC risk. The annual incidence of HCC in HBsAg-positive cirrhotic patients is 2-5%, and even in non-cirrhotic chronic HBV patients with significant fibrosis, annual incidence reaches 0.2-0.5%.

HCV accounts for 15-30% of HCC cases globally and is the leading cause in Japan and many developed nations. HCV obligately causes HCC through cirrhosis (rarely without cirrhosis), operating primarily through chronic inflammation, oxidative stress, and fibrosis rather than direct viral oncogenicity. The NS5A and NS5B proteins promote cell proliferation and inhibit apoptosis. Risk is highest in patients with cirrhosis (annual HCC incidence 3-8%), and the risk increases substantially with advancing age and male gender. Importantly, direct-acting antiviral (DAA) therapy achieving sustained virologic response significantly reduces (though does not eliminate) HCC risk even in advanced fibrosis.

Chronic excessive alcohol consumption causes hepatocyte necrosis, lipotoxicity, and oxidative stress leading to cirrhosis, which is the HCC risk factor itself. Alcohol-related cirrhosis accounts for 10-25% of HCCs in Western countries. The mechanisms include generation of acetaldehyde (highly toxic metabolite), lipid peroxidation, impaired hepatocyte regeneration, and dysbiosis with increased bacterial translocation. The annual HCC incidence in alcohol-related cirrhosis is 1-3%, and males are disproportionately affected.

NAFLD/NASH is rapidly emerging as a major HCC risk factor, now accounting for 10-20% of new HCC cases in Western countries and projected to become the leading cause. NASH develops through hepatic steatosis, lipotoxicity, mitochondrial dysfunction, oxidative stress, and hepatic inflammation. HCC can develop in NASH-related cirrhosis, but importantly, an increasing proportion of HCC cases arise in non-cirrhotic NASH due to metabolic syndrome effects. The annual HCC incidence in NASH-related cirrhosis is 2-3%.

Patients with PBC or PSC complicated by cirrhosis have elevated HCC risk. The mechanisms relate to chronic cholestatic inflammation, oxidative stress, and cirrhosis rather than primary biliary/sclerosing pathology. The annual incidence in cirrhotic PBC/PSC is 1-2%.

Iron overload causes hepatocyte iron deposition leading to oxidative stress, lipid peroxidation, and increased ROS generation. Approximately 10-15% of hemochromatosis patients develop cirrhosis, and of those, the annual HCC incidence is 1-3%. Genetic testing for HFE mutations is standard in hemochromatosis screening. Iron chelation therapy can reduce HCC risk if begun before cirrhosis develops.

Any etiology causing cirrhosis increases HCC risk. Alpha-1 antitrypsin (AAT) deficiency carries particularly high HCC risk once cirrhosis develops. Autoimmune hepatitis, viral hepatitis D (delta) (only in HBsAg-positive patients), and Wilson disease are less common causes but carry HCC risk proportional to cirrhosis severity.

The clinical presentation of HCC is highly variable and largely depends on tumor stage, underlying liver synthetic function, and the degree of hepatic decompensation. Many patients are asymptomatic at early stages and are detected through surveillance imaging.

This is the most common symptomatic complaint, occurring in 30-50% of symptomatic patients. Pain results from capsular distension by the expanding tumor mass, inflammation, or hemorrhage within the tumor. The pain is often dull, persistent, and may radiate to the right shoulder if there is diaphragmatic irritation. Acute severe pain suggests intrahepatic hemorrhage or capsular rupture.

These symptoms reflect hepatomegaly from the primary tumor, underlying cirrhotic changes, or portal hypertension with ascites. Patients note progressive abdominal girth increase and diminished appetite due to gastric compression. These are common presenting symptoms in advanced disease.

Cachexia and unintentional weight loss occur in 10-20% of patients at presentation, reflecting increased metabolic demands from the tumor, systemic inflammatory response, and impaired hepatic synthetic function. Malaise, fatigue, and low-grade fever may accompany tumor necrosis and inflammatory cytokine production.

These symptoms indicate either advanced HCC with hepatic synthetic dysfunction or biliary obstruction from a tumor compressing the biliary tree or producing extrahepatic metastases. Jaundice reflects hyperbilirubinemia from hepatocyte injury or biliary obstruction. Pruritus correlates with bile acid accumulation.

These indicate gastrointestinal bleeding, most commonly from esophageal varices secondary to portal hypertension, though bleeding from a bleeding HCC nodule eroding into a vessel can occur. Acute hemodynamic instability in this setting represents a medical emergency.

A firm, enlarged liver with an irregular surface is present in 50-60% of cases. The liver edge may be palpable below the right costal margin, and there may be an audible bruit over the liver (indicating vascular flow through tumor vessels) in 5-15% of cases—a classic but rare sign.

Spider angiomas, palmar erythema, gynecomastia, testicular atrophy, and ascites reflect underlying cirrhosis and portal hypertension rather than the HCC per se. Ascites is present in 40-60% of cirrhotic patients at HCC presentation and may be new-onset or worsening in previously stable patients.

Present in 20-30% of patients, reflecting portal hypertension with splenic congestion and sequestration.

Visible in 10-20% of patients with advanced disease or significant hepatic synthetic dysfunction.

Evident in advanced disease with significant weight loss.

A substantial proportion (30-50%) of HCC is detected incidentally on surveillance imaging in at-risk patients before symptoms develop. This represents a major advantage of surveillance programs, as earlier-stage disease is more amenable to curative therapies. These patients may have no symptoms whatsoever and normal liver function tests.

Rarely, HCC can present acutely with massive hepatic necrosis, coagulopathy, encephalopathy, and multi-organ failure. This is more common in Asian populations with HBV-related HCC and carries an extremely poor prognosis.

Some patients present with symptoms of metastatic disease (lung, bone, brain, adrenal) before hepatic disease is fully appreciated. Lung metastases are most common and may present with cough or dyspnea.

Spontaneous rupture of HCC (particularly in the left lobe) causes acute peritoneal bleeding with severe abdominal pain, hypotension, and hemorrhagic shock. This is a surgical emergency with mortality >50% even with intervention.

The diagnosis of HCC involves a stepwise approach integrating clinical context, imaging characteristics, and biomarkers, with final diagnosis confirmed through imaging criteria or histopathology.

Any patient with cirrhosis of any etiology or with chronic HBV (even without cirrhosis in some cases) presenting with new symptoms suggestive of liver disease or with incidental imaging findings should raise suspicion for HCC. Similarly, patients with NAFLD-related cirrhosis or other chronic liver diseases warrant surveillance.

AFP is an oncofetal protein elevated in 50-70% of HCC cases and serves as a biomarker for diagnosis and monitoring. Levels >400 ng/mL are highly suggestive of HCC in the appropriate clinical context. However, AFP is not specific (elevations occur in hepatitis flares, regenerating cirrhosis, and other conditions) and not sensitive enough for early detection (only 20% of small HCCs have elevated AFP). Des-gamma-carboxyprothrombin (DCP) and AFP-L3 fraction are alternative biomarkers with different sensitivities and specificities. In surveillance programs, rising AFP trend over time is more informative than absolute value. AFP is useful for post-treatment monitoring and prognostication.

Bilirubin, alkaline phosphatase, and transaminases reflect the degree of hepatic synthetic dysfunction and cholestasis. Elevated levels indicate more advanced disease and worse prognosis. Albumin and INR reflect hepatic synthetic function and correlate with prognosis. The Model for End-Stage Liver Disease (MELD) score incorporates creatinine, bilirubin, and INR to assess liver function reserve.

Thrombocytopenia reflects portal hypertension and bone marrow suppression, while anemia may

Therapy is chosen by Barcelona Clinic Liver Cancer (BCLC) stage, which integrates tumor burden, performance status, and residual liver function (Child-Pugh class) — a framework endorsed by the AASLD HCC guidance and NCCN Hepatobiliary Cancers guidelines.