Kidney disease in very long‐term survivors of Wilms tumor: A nationwide cohort study with sibling controls

BACKGROUND: Survival after Wilms tumor has significantly increased and focus on late effects has become increasingly important. However, knowledge about long‐term renal function in survivors of Wilms tumor is missing. Our aim was to investigate evidence of kidney disease in 20‐ or more‐year survivors of Wilms tumor in a clinical setting, with siblings as comparisons. METHODS: In this cross‐sectional study, we established a cohort of Danish 20‐plus‐year survivors of Wilms tumor and siblings as controls. Participants answered a comprehensive health questionnaire supplemented by measurements of estimated glomerular filtration rate (eGFR), urine albumin‐to‐creatinine ratio, and blood pressure and were categorized according to the chronic kidney disease classification. Multiple linear regression analysis, taking family membership into account, was used to describe the differences in eGFR. Logistic regression analysis was performed to describe risk factors for the development of kidney disease. RESULTS: We included 99 survivors of Wilms tumor and 38 sibling controls with a median of 37 years of follow‐up. The eGFR of Wilms tumor survivors was 13 ml/min/1.73 m(2) (95% CI –20; −5) lower when compared to sibling control. Evidence of kidney disease, with risk factors as hypertension and diabetes, was found in 19% of the Wilms tumor survivors and 2% developed end‐stage renal disease. Ninety‐two percent of the Wilms tumor survivors had an eGFR >60 ml/min/1.73(2). CONCLUSION: Long‐term Wilms tumor survivors have on average a significantly decreased renal function along with the increased prevalence of kidney disease and end‐stage renal disease when compared to sibling controls. Still, most survivors had kidney function within the normal range.