Hepatitis C and Liver Cancer
Hepatitis C virus (HCV) infection is also associated with the development of liver cancer. In fact, in Japan, hepatitis C virus is present in up to 75% of people who have liver cancer. As with hepatitis B virus, the majority of hepatitis C virus patients with liver cancer have associated cirrhosis (liver scarring). In several studies of the natural history of hepatitis C, the average time to develop liver cancer after exposure to hepatitis C virus was about 28 years. The liver cancer occurred about 8 to 10 years after the development of cirrhosis in these patients with hepatitis C. Up to 2.5% of people with chronic hepatitis C infection will go on to get liver cancer.
In hepatitis C virus patients, the risk factors for developing liver cancer include:
- older age
- male gender
- elevated baseline alpha-fetoprotein level (a blood tumor marker)
- heavy alcohol use
- co-infection with hepatitis B virus or HIV
Some earlier studies suggested that hepatitis C virus genotype 1b (a common genotype in the U.S.) may be a risk factor, but more recent studies show conflicting data.
The way in which hepatitis C virus causes liver cancer is not well understood. It is known, however, that cirrhosis from any cause is a risk factor for the development of liver cancer. It has been argued, therefore, that hepatitis C virus, which causes cirrhosis of the liver, is an indirect cause of liver cancer.
On the other hand, there are some chronic hepatitis C virus infected individuals who have liver cancer without cirrhosis. So, it has been suggested that the core (central) protein of hepatitis C virus is the culprit in the development of liver cancer. The core protein itself is thought to impede the natural process of cell death or interfere with the function of a normal tumor suppressor (inhibitor) gene (the p53 gene). The result of these actions is that the liver cells go on living and reproducing without the normal restraints, which is what happens in cancer.