[Viruses and primary hepatocellular carcinoma]

The etiological association between primary hepatocellular carcinoma (PHCC) and chronic viral hepatitis has been proved by now beyond doubt in the hepatitis B virus (HBV) and C virus (HCV). PHCC develops most frequently in cirrhotic livers, sometimes also in the absence of cirrhosis. Extensive epidemiological studies provided convincing evidence of this etiological relationship which is also supported by observations and animal experiments. An important factor in hepatocarcinogenesis due to the influence of HBV is integration of the viral genoma into the liver cell genoma. In the tumourous part of the liver integrated HBV sequences are more frequent than in the non-tumourous part. The integration can produce changes in the genome of the liver cell which may sometimes lead to malignant transformation. The mechanisms of this process are not quite clear so far. Their outcome--the development of carcinoma--can be summarized as the peak effect of factors leading to the disorganization of DNA with participation of chromosomal changes, the action of transactivation of HBs protein, transformation growth factors and the important influence of mutations of the suppressor gene p 53 on the 17th chromosome which is probably the target of HBV. HCV produces chronic live: disease developing into cirrhosis and PHCC, even more frequent than HBV; however its integration into the liver cell does not take place. The genetic variability of this gene is great. Its transformating action is probably implemented rather as a co-carcinogen on the background of cirrhosis of the liver which alone regardless of its cause is an increased risk for the development of PHCC. In clinical practice these findings imply the necessity of optimal prevention of chronic viral hepatic infection (vaccination, so far available for HBV, transfusions) and the necessity to assess the virological status in patients with chronic liver disease and early detection of small tumourous liver lesions where nowadays due to modern therapeutic approaches the prognosis has improved greatly.