Malignancy in renal transplant recipients.

Immunosuppressed organ allograft recipients have a 3-4 fold increased risk of developing cancer, but the chance of developing certain malignancies is increased several hundredfold. With the exception of skin cancers, most of the common neoplasms seen in the general population are not increased in incidence in organ allograft recipients. Instead, there is a higher frequency of relatively rare tumors including lymphomas, Kaposi's sarcoma, other sarcomas, vulvar and perineal carcinomas, renal and hepatobiliary carcinomas. Tumors appear after a relatively short time post-transplantation. The earliest is Kaposi's sarcoma, which appears after an average of 22 months post-transplantation, and the latest are vulvar and perineal carcinomas, which present after an average of 113 months post-transplantation. Unusual features of lymphomas are: (a) high incidence of non-Hodgkin's lymphomas; (b) high frequency of Epstein-Barr virus-related lesions; (c) frequent involvement of extra-nodal sites; (d) marked predilection for the brain; and (e) frequent allograft involvement. Skin cancers also present unusual features: (a) remarkably high frequency of Kaposi's sarcoma; (b) reversal of the ratio of basal to squamous cell carcinomas seen in the general population; (c) young age of the patients; and (d) high incidence of multiple tumors, which occur in 43% of patients. Vulvar and perineal cancers occur at a much younger age than in the general population. Probably, multiple factors play a role in the etiology of the cancers. Immunodeficiency per se and infection with oncogenic viruses may be major influences. Other factors possibly playing a role include direct damage to DNA by various immunosuppressive agents; possibly synergistic effects of these treatments with carcinogens; and genetic factors influencing susceptibility or resistance to development of malignancy.