| Popis: |
Risk factors for skin cancer in organ transplant recipients largely overlap with risk factors that are known in the nonimmunosuppressed population and consist of a complex interplay between environmental and host-related factors. Well-known environmental risk factors are exposure to sunlight [1–3], ionizing radiation [4–6], and various chemical carcinogens. Infections with certain viruses are also likely to be involved in skin cancer carcinogenesis. Human herpes virus type 8 is almost always present in Kaposi’s sarcomas [7–9]; mucosal human papillomaviruses play an important role in the development of cervical carcinoma and anogenital carcinomas [10–12]; and beta papillomaviruses are thought to play a role in the development of cutaneous squamous cell carcinoma and possibly basal cell carcinoma [13–16]. Increasing age is an important nongenetic, host-related factor for the development of skin cancer [17–19]. Other host-related risk factors for skin cancer include genetic factors such as male sex, fair complexion, inability to tan, and nongenetic factors such as chronic scars and ulcers of the skin [20, 21]. Well-known genes that influence skin cancer susceptibility are, among others, melanocortin 1 receptor variants (MCR1); nucleotide excision repair (NER) genes, involved in xeroderma pigmentosum; the p53 tumor suppressor gene; stat 3 regulated genes (c-myc, cdc25A, COX 2); the IkB kinase gene; human leukocyte antigens (HLA); and many other possible genes [22–30]. In organ transplant recipients, long-term immunosuppressive therapy forms one of the most important risk factors [31,32]. Specifically, cumulative doses of immunosuppressive agents play a role, but there may also be differences in the carcinogenic potential of the different immunosuppressive agents. Prospective randomized studies with skin cancer as the final outcome are still lacking, and therefore one has to rely on retrospective follow-up studies with differences in the immunosuppressive regimens. Conclusions based on these types of studies are not always reliable. Donor-related factors, such as HLA and other antigens that are present in the transplanted organ but not present in the recipient, are additional potential risk |
