Hepatocellular Carcinoma (HCC)
Hepatocellular carcinoma (HCC), also known as a hepatoma, is a type of primary liver cancer that originates in liver cells (hepatocytes). Hepatocellular carcinoma is the most common primary cancer of the liver, is the 6th most common cancer worldwide. In the United States, HCC is the fastest growing cause of cancer related death with a 5-year survival of less than 12%.
It most often occurs in adults with cirrhosis and viral hepatitis B or C. Nonalcoholic steatohepatitis (NASH) in the presence of cirrhosis is a recently recognized risk factor for HCC and is expected to be one of the leading causes of HCC over the next decade. There are reports of HCC developing in individuals with NASH in the absence of cirrhosis, however the specific risk factors and rates of this is still being studied. Importantly, HCC can be a complication of cirrhosis from any cause (alcohol, Wilson disease, or hemochromatosis (excess iron in the body)).
HCC is largely asymptomatic until it is very advanced. As the tumor progresses, there may be vague symptoms such as weight loss, fatigue, or nausea. Worsening liver function may occur when the tumor fills the liver and can present as jaundice (yellowing of the skin), swelling or confusion. Late in the course, pain or rarely bleeding into the abdomen may occur.
Surveillance with Ultrasound (US) imaging every 6 months is recommended in patients with cirrhosis. Some providers may check serum α-fetoprotein (AFP) levels, a protein that is suggestive of HCC when found at high or rising levels.
Any liver mass noted on US in the setting of advanced liver disease or cirrhosis requires further investigation. The patient should be referred for either triple phase computer tomography (CT) imaging or magnetic resonance imaging (MRI). It is rare, that a liver mass that is suspected to be HCC is biopsied to establish the diagnosis. Radiographic diagnosis is the standard of care for HCC. As is the case with any type of liver tumor, outcomes are generally more favorable when HCC is diagnosed and treated in its earliest stages.
Ablative therapy is commonly used for one or few hepatocellular carcinoma tumors that are < 5 cm in size. Ablation is performed by the insertion of a needle or a probe into the liver tumor through the skin and delivering a form of high energy to destroy the tumor cells. It is typically used in patients when surgery is not a good option such as in patients with poor general health or decreased liver function. Ablative therapy can be done in different ways including the following:
Radiofrequency ablation (RFA), which uses a high-frequency current that is passed through the tip of the probe to heat and destroy the tumor.
Microwave thermotherapy, which uses microwaves that are transmitted through the probe to heat and destroy the tumor.
Embolization includes the placement of a catheter into an artery through a cut in the inner thigh or wrist and then threading the catheter up into the artery that feeds the liver tumor (hepatic artery) to inject micro beads that will block blood flow to the tumor. The same procedure can also be used to deliver chemotherapy (trans-arterial chemoembolization or TACE) or radiation therapy (trans-arterial radioembolization or TARE) directly to the cancer cells.
Embolization is an option for patients with tumors that cannot be removed by surgery or those that are too large to be treated with ablation therapy (larger than 5 cm). It can also be used with ablation. The ablative therapies are often used while patients are awaiting liver transplantation. These therapies are not curative.
In the case of liver cancer, the transplant team can decide if surgical resection is the best treatment and this is usually when the liver has normal function. The ideal patient for resection has only one liver lesion confined to the liver that shows no radiographic evidence of invasion of the liver vessels, no evidence of increased pressure in the liver (portal hypertension), and has well-preserved liver function.
Although many surgeons only perform resection in patients with tumors ≤5 cm in diameter, there is no general rule regarding tumor size for selection of patients for resection. Patients with a single liver cancer tumor without invasion of the liver vessels have a similar survival probability regardless of tumor size, although patients with smaller tumors tend to have a better outcome. Proper assessment of overall liver function is important when selecting patients who are eligible for resection.
Liver transplantation is the best treatment for liver cancer in patients with cirrhosis and who also have associated portal hypertension. Liver transplantation is a suitable option for patients with cirrhosis who would not tolerate liver resection and who have a solitary liver cancer tumor ≤5 cm in diameter but greater than 2cm or up to three separate tumors none of which is larger than 3 cm. Some transplant centers have extended criteria to widen the indications for liver transplantation. Patients with liver cancer tumors that are within transplant criteria are eligible to receive Model for End-Stage Liver Disease (MELD) exception points at set time intervals. The goal is for these patients to be transplanted before their tumor burden exceeds transplant criteria. Patients with hepatocellular carcinoma who are within transplant criteria are offered MELD exception points that are used to prioritize patients on the liver transplant list. Therefore, the higher the MELD score, the higher the patient is on the liver transplant list.