PATHOGENESIS. Organ transplant recipients (OTRs) are a special group of patients with important characteristics and unique medical needs. Because squamous cell carcinomas (SCC) in OTRs tend to be common, with more aggressive local invasion, early recurrence, and higher rates of metastases, the recognition and treatment of skin cancer, especially SCC, in these patients is becoming a more important aspect of their overall care. As OTRs live longer with better antirejection regimens, the incidence of metastatic SCC in these patients will most likely increase. The pathogenesis of malignancies, specifically SCC in OTRs, is multifactorial. The immunosuppression required in OTRs is a well-documented factor in the development of SCC and other malignancies. In fact, cancer of any type is three to four times more likely to develop in OTRs than in the general population. Immunosuppression not only predisposes OTRs to the development of SCC but also increases tumor aggressiveness, the chance of metastatic disease, and the possibility of death. The level and duration of immunosuppression is the single most important factor influencing malignant transformation and metastasis in OTRs. This is well illustrated by cardiac transplant patients, who generally receive higher levels of immunosuppression than recipients of other types of organ transplants and have the highest rate of SCC among OTRs. Moloney et al. postulated that immunosuppression can affect whether a local primary SCC transforms into a tumor with the potential to metastasize. Immunosuppression may increase the incidence of SCC through at least two mechanisms.
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