[Precancerous stages of hepatocellular carcinoma]

Precancerous stages of hepatocellular carcinoma (HCC) may be broadly categorized into three groups: high risk group, chronic liver diseases and adenomatous hyperplasia nodule. The high risk group for HCC has been clearly defined as the HCC which in Japan develops exclusively in patients with chronic liver diseases due to persistent infection of HBV or HCV. The mechanisms of HCC development by these hepatitis viruses have been partly clarified, and our study has shown it takes 25 years on average from HCV infection to the diagnosis of small HCC. Secondly, almost all cases of HCC are accompanied with chronic liver diseases, especially cirrhosis. Thus, cirrhosis has been considered as a precancerous stage. Recent studies indicated that BrdU labeling index is significantly increased in the non-cancerous cirrhotic portion in the cirrhotics with HCC, suggesting HCC develops in cirrhotics with high DNA synthetic potency of hepatocytes. Lastly, adenomous hyperplasia has also been considered a precancerous stage of HCC because early HCC is often seen in the nodule of this lesion. In addition, the early HCC nodules are diagnosed by serial liver biopsy in following patients with adenomatous hyperplasia. Thus, this lesion is considered the precancerous stage of HCC in a narrow sense. However, the early HCC nodules developing in adenomatous hyperplasia lesions are not all early HCC.