Uncovering the Risk: Incidence of Upper Tract Urothelial Carcinoma Following Renal Transplantation in the Netherlands

Background and objective: Renal transplant (RTx) recipients appear to have an elevated risk of urothelial carcinoma compared with the general population. While Asia reports a high incidence of upper tract urothelial carcinoma (UTUC) following RTx, this incidence remains underinvestigated in Western countries. The main objective of this study is to determine the incidence of UTUC after RTx in the Netherlands, and to evaluate and compare the incidence and tumour characteristics with those of the general Dutch population diagnosed with UTUC. Methods: A retrospective nationwide analysis was conducted using data from the Dutch Pathology Registry on patients with UTUC after RTx between 1991 and 2023. We analysed patient and tumour characteristics, and treatment details. Key findings and limitations: Out of 24 270 RTx patients (1991–2023), 30 developed UTUC, showing a 0.12% cumulative incidence and a 3.7 per 100 000 person-years incidence rate. The median age at UTUC diagnosis was 59 yr, and 47% had grade 3 UTUC. The overall incidence of UTUC in the Dutch population between 1991 and 2023 is 3.3 per 100 000 using the revised European standardised rate, with a median age of 71 yr and 40% grade 3 UTUC. Given that the study is retrospective, an inevitable bias needs to be considered. Conclusions and clinical implications: We found a modestly higher incidence of UTUC after RTx within the Netherlands, with patients showing a lower median age at diagnosis and a higher percentage of grade 3 tumours than the general Dutch population diagnosed with UTUC. Patient summary: In this report, we evaluated the incidence of upper tract urothelial cancer in patients who received kidney transplantation. Outcomes suggest a modestly higher incidence in patients after kidney transplantation than in the general Dutch population diagnosed with upper tract urothelial cancer.