Cutaneous melanoma is related to immune suppression in kidney transplant recipients

Melanoma incidence is increased after organ transplantation, but there is uncertainty as to why this occurs. Diagnoses of invasive melanoma were ascertained in 8,152 kidney transplant recipients (1982-2003) by linking national Australian population-based registers, the Australia and New Zealand Dialysis and Transplant Registry, and the Australian National Cancer Statistics Clearing House. Incidence rate ratios (IRR) and standardized incidence ratios were used to compare melanoma risk during periods of transplant function and failure. Standardized incidence ratios were also computed by time since transplantation. Risk factors were examined using multivariate Poisson regression. Linkage identified 82 melanomas (134/100,000 person-years). Incidence was lower after resumption of dialysis and reduction of immune suppression than during transplant function [IRR, 0.09; 95% confidence interval (95% CI), 0.01-0.66]. During first transplant function, melanoma (n = 74) relative risk peaked in the second year and declined linearly thereafter (P trend = 0.03). During first transplant function, risk was positively associated with increasing year of age (IRR, 1.05; 95% CI, 1.03-1.07) and receipt of lymphocyte-depleting antibody (IRR, 1.73; 95% CI, 1.05-2.84). Female sex (IRR, 0.57; 95% CI, 0.35-0.94), non-Caucasian race (IRR, 0.15; 95% CI, 0.02-1.05), and increasing time since transplantation (P trend = 0.06) were inversely associated with risk. The incidence pattern and risk factor profile for melanoma after transplantation strongly suggest that the current receipt, intensity, and possibly the recency of iatrogenic immunosuppression increase melanoma risk. Melanoma risk was also associated with proxy indicators of high personal sun exposure and sensitivity. These findings show the marked influence of immunologic control over melanoma incidence.