Standard kidney function tests underestimate chronic kidney disease in cancer patients, study finds

Research presented at ASN Kidney Week 2026 shows standard creatinine-based kidney function tests significantly underestimate chronic kidney disease in cancer patients. Among 1,200 adults with solid tumors, measured kidney filtration revealed a 18.9% disease prevalence compared to 10.2% detected by standard tests. Dr. Veronica Torres Costa e Silva noted that inaccurate filtration estimates lead to excessive dosing of therapies like cisplatin, exposing patients to heightened drug toxicity risks.

Standard eGFR tests underestimate CKD prevalence

• ▪Among cancer patients with measured GFR between 45 and 59 ml/min/1.73 m² in the study, 72.1% had creatinine-based eGFR above 60, misclassifying them as having normal kidney function.
• ▪Adding cystatin C to creatinine in estimated glomerular filtration rate tests improved filtration estimation accuracy in cancer patients, but concordance with direct measured glomerular filtration rate remained poor.
• ▪In a University of São Paulo Medical School study of 1,200 adults with solid tumors, standard estimated glomerular filtration rate tests underestimated chronic kidney disease prevalence compared to direct measured glomerular filtration rate.
• ▪In a study of 1,200 adults with solid tumors presented at ASN Kidney Week 2026, chronic kidney disease prevalence was 18.9% by measured GFR, 10.2% by creatinine eGFR, and 15.7% by combined creatinine and cystatin C eGFR.

Inaccurate GFR estimation risks severe drug toxicity

• ▪Standard medical guidelines specify that cancer patients with GFR of 45–60 ml/min/1.73 m² require a 25% to 50% cisplatin dose reduction, while patients with GFR below 45 ml/min/1.73 m² are ineligible for cisplatin.
• ▪Errors in GFR estimation for cancer patients can lead to improper drug eligibility determinations and inaccurate dose adjustments because drug clearance rates drop as kidney function declines.
• ▪Inaccurate GFR estimation causes cancer patients to receive excessively high doses of cisplatin and experience higher treatment toxicity, according to Dr. Veronica Torres Costa e Silva of the University of São Paulo Medical School.