Paediatric cancer survivors demonstrate a high rate of subclinical renal dysfunction

Abstract

Background: Clinical manifestations of renal dysfunction in childhood cancer survivors include hypertension, proteinuria, tubulopathy (and its biochemical consequences) and renal insufficiency. This study aimed to determine the factors associated with renal dysfunction in paediatric cancer survivors at a single centre in Johannesburg.

Procedure: A descriptive cross-sectional study was performed on 130 cancer survivors between 2 and 18 years of age. Physical examination and screening urine dipstick were performed on all patients. Blood results of samples routinely drawn were analysed.

Results: After a median follow-up period of 2 years, the various manifestations of renal dysfunction included decreased estimated glomerular filtration rate (eGFR), hypomagnesaemia, hypophosphataemia, proteinuria, haematuria and hypertension. In total, 34 survivors (26.15%) had at least one manifestation of renal dysfunction after completing treatment. The most prevalent manifestation of renal dysfunction was decreased eGFR (17.7%) followed by hypomagnesaemia (6.2%) and hypophosphataemia (4.6%). Patients with pre-existing renal dysfunction were three times more likely to have renal dysfunction post-treatment (P = 0.020). Ifosfamide (P = 0.010) and nephrectomy (P = 0.003) had independent significant impact on reduction in eGFR. High cumulative ifosfamide doses were identified as a possible cause for hypophosphataemia (P = 0.021).

Conclusion: While not clinically evident in the early follow-up period, the high rate of renal dysfunction is concerning. We suggest that patients with pre-existing renal dysfunction should be assessed by a nephrologist prior to initiation of cancer therapy, and nephro-protective measures should be employed stringently in all children with cancer. Patients with decreased eGFR should be followed up closely in a multidisciplinary late effects clinic.

Keywords: cancer; paediatric; subclinical renal dysfunction; survivors.