Neoplasia and organ transplantation.

Introduction. - Organ transplantation is associated with an increased risk of neoplasia, which seems to be caused by the total effect of immunosuppres sion, i.e., the combination of factors involved, rather than by the use of a specific class of immunosuppressants. The presence and proliferation of v iral oncogenes is frequently observed during this immunosuppressive state. The neoplasia in immunosuppressed patients therefore has particular histolo gical, clinical, evolutive, and therapeutical characteristics. Current knowledge and key points. - The oncogenic mechanisms in immunosuppr essed patients have been progressively clarified. A viral infection is asso ciated with each type of neoplasia: thus, B lymphoma are generally associat ed with Epstein-Barr viral infection. Skin and uterine cervical carcinomas frequently appear after viral dysplasia due to papillomavirus. The signific ant increase in the incidence of Kaposi sarcoma shows the role of the immun e system in the control of the infection by the human herpes virus 8, which has been recently discovered. Liver cancer is associated with a history of hepatitis B or C chronic infection. Future prospects and projects. - Post-transplantation neoplasia constitutes a major problem in patient follow-up, as the number of transplant patients has increased and their survival rare has improved. In addition, there is an increasingly powerful new generation of immunosuppressive drugs. A preci se knowledge of the immune system's control mechanisms regarding neoplasic cells and viral infection is an important step in the prevention and effici ent treatment of these forms of cancer Further research into the relationsh ip between the immune system and viral oncogenesis should therefore be cons idered a major aim. (C) 1999 Editions scientifiques et medicales Elsevier S AS.