Context: Immune suppression after organ transplantation is associated with a markedly increased risk of nonmelanoma skin cancer and a few virus-associated cancers. Although it is generally accepted that other cancers do not occur at increased rates, there have been few long-term population-based cohort studies performed.
Objective: To compare the incidence of cancer in patients receiving immune suppression after kidney transplantation with incidence in the same population in 2 periods before receipt of immune suppression: during dialysis and during end-stage kidney disease before renal replacement therapy (RRT).
Design, setting, and participants: A population-based cohort study of 28,855 patients with end-stage kidney disease who received RRT, with 273,407 person-years of follow-up. Incident cancers (1982-2003) were ascertained by record linkage between the Australia and New Zealand Dialysis and Transplant Registry and the Australian National Cancer Statistics Clearing House.
Main outcome measure: Standardized incidence ratios (SIRs) of cancer, using age-specific, sex-specific, calendar year-specific, and state/territory-specific population cancer incidence rates.
Results: The overall incidence of cancer, excluding nonmelanoma skin cancer and those cancers known to frequently cause end-stage kidney disease, was markedly increased after transplantation (n = 1236; SIR, 3.27; 95% confidence interval [CI], 3.09-3.46). In contrast, cancer incidence was only slightly increased during dialysis (n = 870; SIR, 1.35; 95% CI, 1.27-1.45) and before RRT (n = 689; SIR, 1.16; 95% CI, 1.08-1.25). After transplantation, cancer occurred at significantly increased incidence at 25 sites, and risk exceeded 3-fold at 18 of these sites. Most of these cancers were of known or suspected viral etiology.
Conclusions: Kidney transplantation is associated with a marked increase in cancer risk at a wide variety of sites. Because SIRs for most types of cancer were not increased before transplantation, immune suppression may be responsible for the increased risk. These data suggest a broader than previously appreciated role of the interaction between the immune system and common viral infections in the etiology of cancer.