Infection and cancer: current state of art.

Empirical evidence of the association of cancer with parasitic and viral infectious agents has been recognized earlier. Today, viruses are thought to account for about 10% of all cancers and they take a central place in experimental cancer research. This area has expanded tremendously with modern molecular biology techniques, the knowledge of gene expression, cellular enzyme and mechanisms of transformation. However, the last proof of causality is not yet available. Serologic, virologic, experimental and protective evidence is needed to confirm the assumptions in this rapidly developing field of research. The prevention of hepato-cellular carcinoma by effective vaccines now available is, in the opinion of the WHO, at least theoretically possible.