Pathogenesis of nonmelanoma skin cancers in organ transplant recipients

Nonmelanoma skin cancer (NMSC) is the most common human cancer, with an incidence of more than 1.2 million per year in the USA. The risk for the development of NMSCs increases by approximately 10–250 fold in chronically immune suppressed organ transplant recipients (OTRs). Solar UVB is the most common etiologic factor in the development of this neoplasm, both in immune competent and immune suppressed populations. This review provides a description of NMSC in OTRs. It also provides an account of the various immunologic and non-immune-dependent mechanisms involved in the pathogenesis and progression of NMSCs in OTRs. Finally, this review addresses possible strategies for the prevention of this cancer, particularly focusing on the aspects that may be incorporated to prevent negative effects of chemopreventive chemicals on graft survival.

Research highlights
► Organ transplant recipients are at a high risk for developing nonmelanoma skin cancers.
► Skin cancers in OTRs are more aggressive, invasive and metastatic than in healthy controls.
► Risk factors in OTRs are level/type/duration of immunosuppression/age at transplant/organ type.
► Immunologic impairments and direct effects of IDs on tumor cells enhance tumorigenesis.
► The best known chemoopreventive agents in OTRs are TOR inhibitors.