The liver, a football-sized organ located in the upper right abdomen, performs hundreds of essential functions, including detoxification, metabolism, and nutrient production. It filters toxins from the bloodstream, produces bile for fat digestion, and regulates blood sugar levels. When cells within this organ grow uncontrollably, it leads to liver cancer. Understanding the different types of liver cancer is important because their origins and characteristics can vary significantly.
Common Primary Liver Cancers
Primary liver cancer originates directly in the liver. The two most common forms are Hepatocellular Carcinoma (HCC) and Intrahepatic Cholangiocarcinoma (ICC).
Hepatocellular Carcinoma (HCC) is the most prevalent type of primary liver cancer, making up approximately 75% of all cases. It develops from hepatocytes, the main cells of the liver. HCC can manifest as a single tumor or as multiple small nodules scattered throughout the liver, often seen in individuals with underlying chronic liver damage like cirrhosis. Risk factors for HCC include chronic infections with hepatitis B or C viruses, and alcoholic liver disease.
Intrahepatic Cholangiocarcinoma (ICC) is the second most common primary liver cancer, arising from the cells lining the bile ducts within the liver. These bile ducts are a network of tubes that transport bile, a digestive fluid, from the liver to the small intestine. ICC accounts for about 10% to 20% of all primary liver cancers. This type of cancer is often aggressive and can be challenging to diagnose early due to vague symptoms.
Secondary Liver Cancer
Secondary liver cancer, also known as metastatic liver cancer, is distinct from primary liver cancer because it originates elsewhere in the body and then spreads to the liver. This occurs when cancer cells break away from a primary tumor, travel through the bloodstream or lymphatic system, and form new tumors in the liver. The liver’s rich blood supply makes it a common site for these secondary growths.
This type of liver cancer is often more common than primary liver cancer. The nature of the cancer cells in the liver is the same as the original tumor; for example, if colon cancer spreads to the liver, the cells in the liver are still colon cancer cells.
Many different cancers can metastasize to the liver. Cancers of the gastrointestinal tract are particularly prone to spreading to the liver, with colorectal cancer being the most common primary source. Other primary sites that frequently lead to liver metastases include the breast, lung, pancreas, stomach, and esophagus.
Less Common Primary Liver Cancers
Beyond HCC and ICC, several other types of cancer can originate in the liver, though they are much rarer. These less common primary liver cancers often have unique characteristics or affect specific populations.
Fibrolamellar Hepatocellular Carcinoma (FLHCC) is a rare variant of HCC, typically affecting adolescents and young adults under 40 years old. Unlike conventional HCC, FLHCC develops in individuals with otherwise healthy livers and is not associated with cirrhosis or chronic viral hepatitis. This distinct form of liver cancer is characterized by specific fibrous bands within the tumor.
Angiosarcoma is another rare primary liver cancer. This aggressive cancer originates in the cells lining the blood vessels within the liver. It is diagnosed in older individuals and progresses rapidly.
Hepatoblastoma is a rare type of liver cancer that primarily affects children. Most cases are diagnosed in infants and young children under the age of three. This tumor originates from immature liver precursor cells and is the most common liver cancer in the pediatric age group.