Malignancy following renal transplantation

A markedly increased incidence of malignancy in transplant recipients is well recognized. However, the incidence and pattern of post-transplantation malignancies shows some discrepancy among different reports. The renal transplant recipients monitored at Taichung Veterans' General Hospital comprise the largest group in Taiwan. An analysis of the characteristics of post-transplant malignancies emphasizes the differences from malignancies that occur in the Taiwanese general population and those reported in Western countries.

The incidence and characteristics of de novo malignancy in 390 renal transplant recipients who underwent renal transplantation between May 1983 and June 1996 were analyzed. A total of 232 men and 158 women (mean age at transplantation: 38.5 +/- 10.7 years) were included. The relative risk for developing malignancies was calculated based on the sex- and age-matched cancer incidence of reference for the Taiwanese population; data from the Cancer Registry Annual Report in Taiwan (1989) was obtained for comparison.

A total of 25 cancers were diagnosed in 24 renal transplant recipients, for an incidence of 6.2%. The relative risk of renal malignancy was 13.8-fold higher among transplant recipients than in the general population. The impact of gender and age on the development of post-transplantation malignancy was not significant. The most common types of cancer were transitional cell carcinoma (TCC) of the urinary tract (8/25), and hepatoma (8/25), followed by two cases of Kaposi's sarcoma. Aside from immunosuppressive agents, the high incidence of hepatoma and TCC may be attributed to the high incidence of hepatitis infection and the possible carcinogenic effect of abnormal milieu induced by uremia per se. Survival was largely dependent on the extent of disease at presentation, and post-transplantation cancer did not show more aggressive behavior if detected early.

The high cumulative incidence of malignancies makes it imperative to define an effective safe immunosuppressive regimen to achieve a lower risk of malignancies. In the future, the prime approach to treatment of post-transplantation malignancies should begin with early detection and ensuing aggressive treatment to improve the outcome.