Risk of basal cell carcinoma in Swedish organ transplant recipients: a population-based study.

BACKGROUND: Risk of basal cell carcinoma (BCC) has been reported to be several-fold increased among organ transplant recipients (OTRs). However, due to lack of reliable BCC registration, population-based risk estimates are scarce. OBJECTIVES: To characterize risk of BCC among OTRs compared with the general population, and contrast with risk of cutaneous squamous cell carcinoma (SCC). SUBJECTS AND METHODS: OTRs transplanted during 2004-2011 were identified through national healthcare registers and linked with the nationwide Swedish BCC Register initialized in 2004. Relative risk of BCC was expressed as standardized incidence ratios (SIR) with 95% confidence intervals (CI). RESULTS: Altogether, 4023 transplanted patients developed 341 BCCs during follow-up. Compared with the general population, the relative risk of BCC was increased sixfold (SIR 6·1, 95% CI 5·4-6·9). The risk was higher in kidney and heart/lung than in liver recipients (SIRkidney 7·2, 6·3-8·3; SIRheart/lung 5·8, 4·0-8·2; SIRliver 2·6, 1·7-4·0), and risk increased with time since transplantation (Ptrend < 0·01). The SCC to BCC ratio was 1 : 1·7 and BCC developed earlier after transplantation than SCC. Distribution of anatomical sites and histological types did not differ substantially between OTR- and population-BCCs. CONCLUSIONS: Risk of BCC was strikingly elevated in OTRs compared with the general population. Risk was higher in kidney recipients and increased with follow-up time. These findings support a tumour-promoting effect of immunosuppressive drugs in BCC development. The low SCC to BCC ratio was possibly attributed to short follow-up time.

Peritumoral dermis of squamous cell carcinomas in renal transplant recipients contains less CD11c+ myeloid dendritic cells and FoxP3+ T cells compared to immunocompetent controls.

BACKGROUND: Renal transplant recipients (RTR) have an increased risk of developing cutaneous squamous cell carcinomas (SCC). These SCC are often more aggressive than SCC in immunocompetent individuals. OBJECTIVES: In this comparative study, we analysed the cell composition in the tissue immediately surrounding invasive SCC in immunosuppressed RTR and immunocompetent controls in an effort to further elucidate the role of the local immune system. METHODS: Morphology and quantity of various dendritic cell (DC) subsets, macrophages and FoxP3+ T cells were analysed by immunohistochemical staining. RESULTS: The number of CD11c+ myeloid DC and FoxP3+ T cells was significantly reduced in RTR, whereas the number of plasmacytoid DC, Langerhans cells and macrophages was similar in RTR and controls. CONCLUSIONS: A reduction in CD11c+ mDC in peritumoral dermis in RTR might contribute to impaired immunosurveillance thus giving rise to an increased risk to develop aggressive SCC in these patients.