Prospective analysis of long-term renal function in survivors of childhood Wilms tumor.

Background: Considering the improved outcome, a better understanding of the late effects in Wilms tumor survivors (WT-S) is needed. This study was aimed at evaluating renal function and determining the prevalence of clinical and subclinical renal dysfunction in a cohort of WT-S using a multimodal diagnostic approach.

Methods: Thirty-seven WT-S were included in this prospective cross-sectional single center study. To evaluate renal function, glomerular filtration rate (GFR) and urinary protein excretion were assessed. Additionally, kidney sonomorphology and blood pressure were analyzed.

Results: All examined WT-S (mean age 28.7 years, mean follow-up 24.8 years) had been treated with a combination of surgery and chemotherapy; 59.5% had received adjuvant radiotherapy. Impaired glomerular renal function was detected in a considerable proportion of WT-S, with age-adjusted cystatin-based GFR estimation below age norm in 55.9%. A lower cystatin-based estimated GFR (eGFR) correlated with longer follow-up time and higher irradiation dose. In 5 patients (13.5%) albuminuria was identified. Analysis of sonomorphology detected compensatory contralateral renal hypertrophy in 83.3% of WT-S. Chronic kidney disease (CKD) ≥ stage II was present in 55.9% of WT-S. Blood pressure measurements revealed arterial hypertension in 15 (40.5%) WT-S (newly diagnosed n=10). In 24.3% both CKD ≥ stage II and arterial hypertension were determined.

Conclusion: Even though WT-S are believed to carry a low risk for end-stage renal disease, in this study, a remarkable number of WT-S presented with previously unidentified subclinical signs of renal function impairment and secondary morbidity. Therefore, it is important to continue regular follow-up, especially after transition into adulthood.