Malignancies in renal transplantation: an unmet medical need

Registry data show that there is an overall 3-5-fold increase in cancer risk in transplant recipients compared with the general population, with skin cancers and lymphoma particularly prevalent. Cancers in transplant recipients are often more aggressive than those in the general population, with poor prognosis, particularly for gastrointestinal tumours and lymphomas. Risk factors for post-transplant malignancy include factors common to the general population, such as increasing age, cigarette smoking and sun exposure. In addition, immunosuppression is an important factor in the development of post-transplantation cancer, although data for individual agents are not definitive. A number of studies have demonstrated that ciclosporin is associated with an increased risk of malignancy, whereas a few studies report no increase in risk of cancer after the introduction of ciclosporin into treatment regimens. Similarly, studies have shown that the mycophenolic acid-based agent mycophenolate mofetil is associated with an increased risk of malignancy, whereas other studies have demonstrated that mycophenolate mofetil is in fact associated with a lower risk. Polyclonal anti-thymocyte antibodies used for induction therapy appear to be related to an increased incidence of post-transplant lymphoproliferative disorder, but this effect is not observed with monoclonal anti-interleukin 2 antibodies. Azathioprine has been implicated in the development of skin tumours, possibly as a result of increased photosensitivity to ultraviolet light. The proliferation signal inhibitors appear to be associated with a reduced risk of some malignancies. Further research will elucidate the role of these newer immunosuppressive agents in post-transplantation malignancies.