Rates of both solid organ and skin cancers after kidney transplantation are substantially increased. However, little is known about the relationship between non-melanoma skin cancer (NMSC) and risk of subsequent immunosuppression.

Using the ANZDATA Registry, we looked at the incidence of solid-organ cancer after kidney transplants performed in Australia or New Zealand from 1975-2011. The Registry records the occurrence of all solid organ malignancies and the first episode of NMSC after transplantation. The occurrence of NMSC post transplantation was used as a time-dependent covariate, and risk of solid organ cancer compared among recipients. Patients were followed from the date of first transplant until death or 31 Dec 2011. In a supplementary analysis, followup was censored at the point of failure of the first graft (and therefore presumed withdrawal of immunosuppression).

The analysis included a total of 18031 transplants, with 139895 person – years of followup prior to first NMSC, and 31459 person-years of followup after a first NMSC. The overall rate of development of solid organ cancer was 1.36 [95% CI 1.30-1.41] per 100 person years, higher among older people, females, and among recipients of deceased donor transplants. The crude hazard ratio for the occurrence of a solid organ malignancy after NMSC was 1.69 [1.53-1.86]; adjusted for age, gender, living vs deceased donor and year of transplant this was 1.22 [1.11-1.36], p<0.001. There was no interaction between the risk of cancer after NMSC and year of transplant.

In supplementary analyses (censored at loss of graft function), a similar excess risk was seen – crude HR 1.56 [1.40-1.74], p<0.001; adjusted for age, gender, donor source and year of transplant this was 1.16 [1.04-1.30]. There was no interaction of this post-NMSC risk with year of transplant, nor with the use of anti-CD3 antibody therapy.

Among kidney transplant recipients, there is an increased risk of solid organ cancer after the occurrence of a NMSC. This risk is independent of other risk factors for cancer such as age, year of transplantation (a proxy for immunosuppression), anti-CD3 use. Whether this relationship marks an underlying propensity to malignant transformation, or an increased vulnerability to the carcinogenic effects of immunosuppressive therapy is not clear.

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