Liver cancer is a disease in which abnormal liver cells multiply uncontrollably and form a mass of cancer cells called a tumor. Cancerous tumors grow destructively and are described as malignant because they invade normal tissue and have a high mortality rate. Liver cancer is dangerous because the body depends on the liver to aid in digestion of food, eliminate toxins, and produce proteins for blood clotting functions.
There are two categories for liver cancer: primary and secondary. Primary liver cancer starts inside the liver. Secondary liver cancer starts in another area of the body and later spreads (metastasizes) to the liver. Most cases of liver cancer are, in fact, metastatic. For example, colon, lung, and breast cancer often spread to the liver. It is very important to distinguish metastatic liver cancer from primary cancer since these conditions are treated differently and therapies for metastatic cancer are based on the part of the body where the cancer originates. The information provided here pertains to primary liver cancer.
There are two types of primary liver cancer: hepatocellular carcinoma (HCC) and cholangiocarcinoma. HCC is the most common primary liver cancer and begins inside liver cells (hepatocytes); whereas, cholangiocarcinoma is much less common and starts in the small tubes of the liver that carry bile (bile ducts).
Several conditions increase the chance of developing primary liver cancer:
Asia and Africa have the highest rates of HCC because of their high incidence of hepatitis B and C. The occurrence of HCC in the United States has been increasing because of hepatitis C and obesity within the population.
In the early stages of primary liver cancer, most patients have no symptoms. When symptoms develop, they may include:
Since 80-90% of liver cancer patients also have cirrhosis, there may be excess fluid in the abdomen (ascites), yellowing of the skin (jaundice), confusion (hepatic encephalopathy), or bleeding.
Physical examination of the abdomen cannot detect small liver tumors, so imaging studies and blood tests are used to make the diagnosis.
Since there are no early symptoms and patients with cirrhosis have a high chance of developing liver cancer, doctors routinely use high-frequency sound waves (ultrasound) to screen these patients. An ultrasound provides a picture of the tumor in the liver.
A blood test is used to detect high levels of a substance produced by liver cancer cells called alpha-fetoprotein (AFP). AFP is considered a tumor marker because it suggests that cancer is present.
Computed tomography (CT) is a type of X-ray that provides a detailed picture of tissues. A magnetic imaging (MRI) scan provides additional views of the liver and an angiogram evaluates blood vessels in the area. If bile duct cancer (cholangiocarcinoma) is suspected, a procedure called cholangiography is used look at the bile ducts.
Some patients are also given a liver biopsy. This is a surgical procedure to remove a small sample of liver tissue for examination under a microscope.
After primary liver cancer is diagnosed, the next step is to determine how far the tumor has spread, which is called the staging of liver cancer. The stage determines the patient’s treatment options and likelihood of survival. Early-stage cancers that are small enough to be cut out with surgery have a better prognosis. Advanced cancers that are large or have spread outside of the liver are considered unresectable, meaning they cannot be cut out with surgery and typically have the worst outcomes. CT helps determine the stage by showing the extent to which the tumor mass has invaded the surrounding tissues. A bone scan is used to check for spread of cancer to the bones.
Surgery to cut out the tumor or replace the liver with one from a donor (liver transplant) offers the best chance for a cure. Organs for liver transplant are in short supply, and some patients are simply not healthy enough for surgery; therefore, many patients are given alternative treatments. Some treatments attempt to destroy cancer cells by freezing them with liquid nitrogen (cryoablation), or heating them with an electric current (radiofrequency ablation). In other treatments, the tumor is injected with substances that destroy cancer such as ethanol, anti-cancer medication (chemoembolization), or radioactive material (radioembolization). These alternative therapies may not completely remove the cancer cells and can predispose the patient to a recurrence of cancer.
Compared to other treatments, a liver transplant offers the best prognosis for long-term survival because all other treatments still leave patients with their underlying liver diseases, cirrhosis, and impaired liver function.
Since primary liver cancer is often caused by cirrhosis, any measures that prevent chronic liver diseases and cirrhosis also prevent liver cancer. Alcohol should not be abused and individuals may help prevent viral hepatitis by avoiding unprotected sex and intravenous drugs. Additionally, a vaccination against hepatitis B has been demonstrated to lower the incidence of liver cancer. Patients with cirrhosis are screened with liver ultrasounds every 6 months to detect cancer as early as possible.