Cancer risk and mortality after kidney transplantation: a population-based study on differences between Danish centres using standard immunosuppression with and without glucocorticoids

Background. Kidney recipients receive immunosuppression to prevent graft rejection, and long-term outcomes such as post-transplant cancer and mortality may vary according to the different protocols of immunosuppression. Methods. A national register-based historical cohort study was conducted to examine whether post-transplant cancer and all-cause mortality differed between Danish renal transplantation centres using standard immunosuppressive protocols including steroids (Centres 2, 3, 4) or a steroid-free protocol (Centre 1). The Danish Nephrology Registry, the Danish Civil Registration System, the Danish National Cancer Registry and the Danish National Patient Register were used. A historical cohort of 1450 kidney recipients transplanted in 1995-2005 was followed up with respect to post-transplant cancer and death until 31 December 2011. Results. Compared with Center 1 the adjusted post-transplant cancer risk was 6-39% lower in Centre 3 [hazard ratio (HR) 0.94, 95% confidence interval (CI) 0.67-1.32], in Centre 2 (HR 0.72, 95% CI 0.52-0.98) and in Centre 4 (HR 0.61, 95% CI 0.44-0.83). Compared with Center 1, the adjusted post-transplant mortality was 21-55% higher in Centre 4 (HR 1.21, 95% CI 0.91-1.61), in Centre 3 (HR 1.35, 95% CI 0.98-1.86) and in Centre 2 (HR 1.55, 95% CI 1.17-2.05). On average, post-transplant cancer was associated with a 4-fold increase in the risk of death (HR 4.25, 95% CI 3.36-5.38). Conclusions. There was a tendency of a higher post-transplant cancer occurrence, but lower all-cause mortality, in the Danish transplantation centre that adhered to a standard steroid-free immunosuppressive protocol.