MALIGNANCY AFTER IMMUNOSUPPRESSIVE THERAPY - HOW CAN THE RISK BE REDUCED

Immunosuppressed organ allograft recipients have a 3- to 4-fold increased risk of developing cancer, but the risk of developing certain malignancies is increased several hundred-fold. Most of the common neoplasms seen in the general population are not increased in incidence, Instead, there is a higher frequency of some relatively rare tumours, including Kaposi's sarcoma, renal carcinomas, other sarcomas, vulvar and perineal carcinomas and hepatobiliary carcinomas, Tumours appear a relatively short time after transplantation. The earliest is Kaposi's sarcoma, which appears an average of 22 months post-transplantation, and the latest to appear are vulvar and perineal carcinomas, which present an average of 113 months after transplantation. Unusual features of the lypmphomas are: (a) the high incidence of non-Hodgkin's lymphomas; (b) a high frequency of Epstein-Barr virus-related lesions; (c) frequent involvement of extranodal sites: (d) a marked predilection for the brain: and (e) frequent allograft involvement Skin cancers also present unusual features: (a) 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) the young age of the patients; and (d) the high incidence of multiple tumours, which are observed in 43% of patients. Vulvar and perineal cancers occur at a much younger age than in the general population. As the immunosuppressed state per sc and various potentially oncogenic viruses play a major role in causing these cancers, preventive measures include reducing immunosuppression to the lowest level compatible with good allograft function and prophylactic measures against certain virus infections. Reduction of exposure to sunlight may also reduce the incidence of skin cancer.