Standard kidney function tests underestimate chronic kidney disease in people with cancer

A University of São Paulo Medical School team reported at ASN Kidney Week 2026 that in 1,200 adults with solid tumors, CKD prevalence based on measured GFR was 18.9%, versus 10.2% with creatinine-based eGFR and 15.7% with combined creatinine/cystatin C estimation. Among patients with mGFR 45–59, 72.1% were classified as normal by creatinine-based eGFR; adding cystatin C improved but did not resolve the discrepancy. Using cisplatin as an example, the authors noted that GFR estimation errors may lead to inadequate dose adjustments and increased toxicity risk.