EN
At the basis of neoplastic processes there lie molecular lesions i.e. non-lethal, multi-stage damage to genetic material. The paper describes damage to nuclear chromatin and the role of RNA in neoplasia as well as the involvement of adhesion molecules, extracellular matrix (ECM), signal transduction (including humoral signals) and the role of cell cycle in the process. The significance of molecular techniques in the diagnosis of tumours was also shown.