[Neoplastic disorders and organ transplantation]

Organ transplantation is associated with an increased risk of neoplasia, which seems to be caused by the total effect of immunosuppression, i.e., the combination of factors involved, rather than by the use of a specific class of immunosuppressants. The presence and proliferation of viral oncogenes is frequently observed during this immunosuppressive state. The neoplasia in immunosuppressed patients therefore has particular histological, clinical, evolutive, and therapeutical characteristics.

The oncogenic mechanisms in immunosuppressed patients have been progressively clarified. A viral infection is associated with each type of neoplasia: thus, B lymphoma are generally associated with Epstein-Barr viral infection. Skin and uterine cervical carcinomas frequently appear after viral dysplasia due to papillomavirus. The significant increase in the incidence of Kaposi sarcoma shows the role of the immune 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.

Post-transplantation neoplasia constitutes a major problem in patient follow-up, as the number of transplant patients has increased and their survival rate has improved. In addition, there is an increasingly powerful new generation of immunosuppressive drugs. A precise knowledge of the immune system's control mechanisms regarding neoplasic cells and viral infection is an important step in the prevention and efficient treatment of these forms of cancer. Further research into the relationship between the immune system and viral oncogenesis should therefore be considered a major aim.