The main cause of liver cancer is hepatitis c. After infecting hepatitis c, virus can be eliminated for 30% of people. And the virus can not be eliminated for 60% of them. Then they become carrier of asymptomatic virus.
As hepatitis c virus gradually breaking liver cellular, the chronic hepatitis c is more and more serious. 30-40% of infector will develop into liver cirrhosis 25 years after infecting. Then after about 10 years, 40%-60% of patients who suffered liver cirrhosis will develop into liver cancer (the end cancer disease). Like what I said just now, the disease is developing in phase and slowly. But the high death rate of liver cancer means hepatitis c virus is definitely a kind of virus caused cancer.
From the blood data of 3.49 million people who done blood donation at first time from 1995 to 2000, we analysis on infection of hepatitis c virus and calculate the number of people who suffered hepatitis c virus in whole Japan according to proportion. Then we know the total number of people suffered hepatitis c virus is over 1.5 million, and many of them will be in risk of liver cancer. The statistics from WHO shows, the spreading rate of hepatitis c virus are 1-2% in Japan, 1.4-1.6% in US, 1.1-1.2% in France, 0.4-0.8% in Britain, and 0.4% in Germany.