The liver is the size of a football and sits in the upper right portion of the abdomen above the stomach. Its job is to clean the blood, produce bile for digestion and store glucose (energy). Hepatocellular carcinoma is the most common form of liver cancer, beginning in the main type of liver cell (hepatocyte).
What Is Liver Cancer?
Liver cancer is a type of cancer that is caused by the abnormal growth of cells in the liver.
The liver is the largest organ in the abdomen. It is located on the right side of the body, behind the right ribs and below the right lung. It is divided into left and right lobes.
The liver gets its blood supply from two sources: the hepatic artery, which supplies the liver with oxygen-rich blood, and the portal vein, which supplies the liver with nutrient-rich blood from the intestines. The portal vein is the liver’s primary source of blood.
The liver performs several functions. It breaks down toxic substances in the blood and gets rid of them. It produces enzymes and bile that help digest food and turn it into substances the body needs to sustain itself and grow. It also produces proteins and clotting factors important in healing.
Growths in the liver can be benign (noncancerous) or malignant (cancerous). Benign growths are generally not life threatening, can often be removed, and do not spread to distant sites in the body. Malignant growths can spread to distant sites in the body and may be life threatening.
The two types of liver cancers are primary liver cancers and secondary liver cancers.
Primary Liver Cancers
Primary liver cancers are cancers that begin in the liver. There are several types of primary liver cancers, but the two most common are:
- Hepatocellular carcinoma (HCC): Hepatocellular carcinoma, also called malignant hepatoma, develops in the hepatocytes (the main type of liver cell). It is the most common form of liver cancer in adults. Approximately 4 out of 5 primary liver cancers are HCCs (American Cancer Society 2015).
- Intrahepatic cholangiocarcinoma (bile duct cancer): Intrahepatic cholangiocarcinoma develops from cholangiocytes (bile duct cells) located inside the liver. These cholangiocytes line the bile ducts, which facilitate excretion of bile produced by the liver. Intrahepatic cholangiocarcinoma accounts for 1 or 2 out of every 10 cases of liver cancer (American Cancer Society 2015).
Secondary Liver Cancers
Secondary liver cancers are cancers that develop in other parts of the body and metastasize (spread) to the liver. The most common of these is cancer of the gastrointestinal tract, like colon cancer. These cancers often require multiple specialists in order to achieve the best survival. Even though these are metastatic cancers, many times the potential of cure is still possible.
Primary liver cancers are the focus of the rest of these pages.
Symptoms of Liver Cancer
Many early-stage liver cancers do not cause symptoms, with symptoms only developing with progression. Common symptoms include:
- Abdominal pain
- A bulge on the right side
- Unintentional weight loss
- Lack of appetite
- Feeling full without eating a lot
- Nausea and vomiting
- Bloating
- Fever
- Yellowing of the eyes (icterus)
- Yellowing of the skin (jaundice), pale stools, and dark urine
- Fatigue
Many of these symptoms can be caused by health problems other than liver cancer. Patients experiencing any of these symptoms should see their physician.
Causes of Liver Cancer
Although the exact causes of liver cancer remain unknown, certain risk factors connected to the disease have been identified. A risk factor is anything that affects one’s chance of getting a disease. While risk factors may be useful in identifying high-risk individuals, they do not determine whether a person develops a disease. Some risk factors, such as alcohol consumption, are within the individual’s control, while others, such as gender, are not.
Possible risk factors for liver cancer include:
- Gender: Men develop liver cancer more often than women.
- Ethnicity: Asian Americans and Pacific Islanders have the highest risk of developing liver cancer.
- Location: The disease is less prevalent in the United States than in other places in the world, such as countries in sub-Saharan Africa and Southeast Asia.
- Hepatitis B virus (HBV) or Hepatitis C virus (HCV): Long-term infection with either of these viruses may increase a person’s risk of developing liver cancer.
- Hemochromatosis: Hemochromatosis is a disease that causes the body to take up and store too much iron. The body stores the excess iron in the heart, liver, and pancreas. The disease may be hereditary (passed on from one’s parents), or it may result from blood transfusions. Having hemochromatosis may increase a person’s risk of developing liver cancer.
- Cirrhosis: Cirrhosis is a disease that develops when liver cells become damaged and are replaced by scar tissue. Infection with HBV and HCV, heavy alcohol consumption, hemochromatosis, and certain drugs and parasites can all cause liver damage. People with cirrhosis are prone to developing liver cancer.
- Environmental factors and toxins: Several environmental factors, such as aflatoxin (a toxic substance produced by certain types of mold that grows on some foods), and toxins, such as tobacco, alcohol, and solvent vinyl chloride (a substance used in the production of plastics), can increase a person’s risk of developing liver cancer.
- Anabolic steroids: Using anabolic steroids (substances that act like the male hormone testosterone) may put a person at greater risk of developing liver cancer.
- Obesity and diabetes: Being obese (very overweight) or having type 2 diabetes may increase a person’s risk of developing the disease.
Liver Cancer Staging
Staging is used to determine the extent of the cancer and treatment options. There are several different staging systems in place for liver cancer. Some staging systems, such as the American Joint Committee on Cancer’s TNM system, look only at how widespread the cancer is. Other systems also take liver function into account.
Physicians frequently categorize liver cancers by whether they can be resected (surgically removed) or not. Surgery is a potential treatment for many patients diagnosed with a tumor or tumors within the liver. These include primary tumors, which originate in the liver, and secondary tumors that develop in other parts of the body and spread to the liver. Staging helps physicians determine the best treatment options for patients.
A liver cancer can potentially be placed into one of five categories:
- A liver cancer is potentially resectable if surgery can be used to remove the cancer, and the health of the patient permits it.
- It is potentially transplantable if the surgeon is able to perform a liver transplant.
- It is unresectable if the surgeon cannot remove the cancer, but it has not spread beyond the liver.
- The cancer is inoperable with only local disease if surgery could be used to remove the cancer, but the health of the patient does not permit it.
- It is metastatic if the cancer has metastasized (spread) beyond the liver. (American Cancer Society 2015)
Liver function is key to determining the best treatment options for patients. A system called the Child-Pugh score helps physicians determine how well the liver is functioning based on the measures of different substances in the blood, fluid in the belly, and brain function.
Patients are encouraged to discuss cancer staging and treatment options with their physicians.
References
American Cancer Society. 2015. Liver Cancer Overview. PDF. http://www.cancer.org/acs/groups/cid/documents/webcontent/003058-pdf.pdf
National Cancer Institute. 2009. What You Need To Know About™ Liver Cancer. PDF. Bethesda: National Cancer Institute, National Institutes of Health, U.S. Department of Health and Human Services. https://ccr.cancer.gov/liver-cancer-program