Skin cancer risk associated with immunosuppressive therapy in organ transplant recipients - Epidemiology and proposed mechanisms

The aim of this review is to summarise the available literature regarding t he epidemiology and proposed mechanisms of skin cancer development in organ transplant recipients who are receiving lifelong treatment with immunosupp ressive therapy and to review the different strategies for managing complic ations in this group of patients. Organ transplantation is complicated by an increased incidence of certain c ancers, of which non-Hodgkin's lymphoma, Kaposi's sarcoma and squamous cell carcinoma are the most common. The most important risk factor for these ca ncers is immunosuppressive therapy. The relative importance of different im munosuppressive therapy regimens in relation to the development of skin can cer is still unclear. Immunosuppression per se may play the most important role, but other mechanisms, which are independent of host immunity and whic h may be different for the various agents used, may also be of importance f or the increased risk of cancer. Apart from immunosuppressive therapy, exposure to sunlight and infection wi th human papillomaviruses are believed to be the most important risk factor s for the development of cutaneous squamous cell carcinoma in organ transpl ant recipients. Human papillomaviruses, no doubt, benefit considerably from immunosuppression, as is indicated by the large number of warts found in t hese patients, but many questions remain unanswered about their significanc e in cutaneous oncogenesis. The E6 protein from a range of cutaneous human papillomavirus types effectively inhibits apoptosis in response to ultravio let light damage. It is, therefore, conceivable that the development of ski n cancer in organ transplant recipients is the result of a complex interpla y between exposure to ultraviolet radiation, human papillomavirus infection and genetic predisposition. Measures for protection from the sun are important for reducing the risk of skin cancer in organ transplant recipients. Regular surveillance of patien ts with skin problems and easy access to a dermatologist for these patients is advised. Changing the immunosuppressive regimen from azathioprine to cy closporin or vice versa does not seem to relieve the skin problems. Taperin g the immunosuppressive therapy to the lowest possible dose may be of some advantage. Oral retinoids, e.g. acitretin, have some effect in reducing the number of keratotic skin lesions and in the prevention of skin cancer in o rgan transplant recipients. Resurfacing the back of the hand can be a succe ssful treatment for patients with multiple skin cancers on the back of the hand and can be used prophylactically in patients with severely actinically damaged skin.