Risk of Thyroid Cancer Among Solid Organ Transplant Recipients

Solid organ transplant recipients have an elevated incidence of thyroid cancer. We evaluated a wide range of potential risk factors in a cohort of 229 300 U.S. solid organ transplant recipients linked with 15 stage/regional cancer registries (1987–2012). Incidence rate ratios (IRRs) were adjusted for age, sex, race/ethnicity, transplanted organ, year of transplantation, and time since transplantation. Hazard ratios (HRs) for death and/or graft failure were adjusted for age, sex, race/ethnicity, transplanted organ, and year of transplantation. After transplantation, 356 thyroid cancers were diagnosed. Thyroid cancer incidence was 2.50-fold higher in transplant recipients than the general population (95% confidence interval [CI] 2.25–2.77). Among recipients of different organs, kidney recipients had the highest incidence of thyroid cancer (IRR = 1.26, 95% CI 1.03–1.53). Elevated thyroid cancer incidence was associated with cholestatic liver disease/cirrhosis as an indication for liver transplantation (IRR = 1.69, 95% CI 1.09–2.63), hypertensive nephrosclerosis as an indication for kidney transplantation (IRR = 1.41, 95% CI 1.03–1.94), and longer prior dialysis among kidney recipients (5+ vs. <1 year, IRR = 1.92, 95% CI 1.32–2.80; p-trend <0.01). Posttransplantation diagnosis of thyroid cancer was associated with modestly increased risk of death (HR = 1.33, 95% CI 1.02–1.73). Overall, our results suggest that end-stage organ disease and longer duration of dialysis may contribute to higher thyroid cancer incidence in transplant recipients.