What is the most common type of liver cancer in adults?

Hepatocellular carcinoma is the most common type of primary liver cancer in adults. NCI's summary for clinicians states that "malignant primary tumors of the liver consist of two major cell types, hepatocellular (90% of cases) and cholangiocarcinoma." Cholangiocarcinoma is bile duct cancer, the other main adult type.

The name says where it starts. Hepatocytes are the liver's main working cells. They filter the blood, store sugar as glycogen, and make bile to help digest fat. Hepatocellular carcinoma begins in those cells. Bile duct cancer begins instead in the tubes that carry bile out toward the small intestine.

One point causes more confusion than any other. NCI is blunt about it: "Cancer that forms in other parts of the body and spreads to the liver is not primary liver cancer." A colon cancer that has spread to the liver is still colon cancer. It is treated with colon cancer drugs. It is not hepatocellular carcinoma. So when a scan report mentions spots in the liver, the first question is whether they started there.

Hepatocellular carcinoma almost never shows up in a healthy liver. NCI reports that cirrhosis is involved in as many as 80% of cases. Cirrhosis is scarring left by years of injury. The mechanism is repetition. Every round of damage forces liver cells to divide and rebuild. Every division is another chance for a DNA error to slip through and stay.

The injuries behind it are mostly known ones. NCI lists "chronic and/or persistent infection with hepatitis B and/or hepatitis C," heavy alcohol use, and "ingestion of foods contaminated with aflatoxin B1," a mold toxin found on poorly stored grain and nuts. It also lists nonalcoholic steatohepatitis, or NASH, which is fatty liver with inflammation.

That background changes how the cancer is treated. With most cancers, doctors stage the tumor. Here they must weigh two things at once, because a person can be lost to liver failure before the tumor does much at all. The system used is Barcelona Clinic Liver Cancer staging, shortened to BCLC. NCI describes "five stages (0 and A through D)" built from tumor stage, liver function, physical status, and symptoms together. Beside it sits the Child-Pugh score. It measures what NCI calls "functional hepatic reserve," meaning how much working liver is left. An operation that would be routine in a healthy liver can be impossible in a scarred one. There is simply not enough spare tissue to survive losing a piece.

This cancer is neither rare nor mild. For 2025 the American Cancer Society projected 42,240 new cases and 30,090 deaths in the United States, and NCI's summary carries that projection. Those two numbers sit uncomfortably close together.

People with cirrhosis are often offered surveillance. That usually means an ultrasound and an alpha-fetoprotein blood test, called AFP, every 6 months. It is worth knowing that NCI's own evidence review is guarded about the practice. Its screening summary concludes that "based on fair evidence, screening of persons at elevated risk does not result in a decrease in mortality from hepatocellular cancer." It also notes AFP sensitivity running anywhere from 39% to 97%, depending on the group studied. Liver specialty groups still recommend surveillance. This is a live question to raise with a liver doctor, not a closed one.

The most useful part of this answer sits upstream of the cancer. Hepatitis B has a vaccine. Hepatitis C has no vaccine, but it is now curable. CDC states that "treatment cures more than 95% of patients with hepatitis C," usually with "8–12 weeks of oral medication," and recommends testing every adult at least once. Alcohol intake and fatty liver can both be changed. If chronic hepatitis or cirrhosis runs in your household, treating the liver disease is the most direct way to lower the risk of this cancer.