Kidney Week

Abstract: SA-PO1256

Effect of the Difference in eGFR Based on Creatinine and Cystatin C on the Overall Survival of Patients with Cancer

Session Information

• Onconephrology: Epidemiological Trends, Risk Stratification, and Clinical Outcomes
  October 24, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Onconephrology

• 1600 Onconephrology

Authors

• Ribeiro, Rayra Gomes, Universidade de Sao Paulo, São Paulo, SP, Brazil

Rayra Gomes Ribeiro, MD

• Inker, Lesley, Tufts University, Medford, Massachusetts, United States

Lesley Inker, MD, MS, FASN

• Kitchlu, Abhijat, University of Toronto, Toronto, Ontario, Canada

Abhijat Kitchlu, MD, MS, MSc

• Caires, Renato A., Universidade de Sao Paulo, São Paulo, SP, Brazil

Renato A. Caires, MD

• Sapienza, Marcelo Tatit, Universidade de Sao Paulo, São Paulo, SP, Brazil

Marcelo Tatit Sapienza, MD, PhD

• Burdmann, Emmanuel A., Universidade de Sao Paulo, São Paulo, SP, Brazil

Emmanuel A. Burdmann, MD, PhD

• Costa e Silva, Veronica Torres, Universidade de Sao Paulo, São Paulo, SP, Brazil

Veronica Torres Costa e Silva, MD, PhD

Background

Estimated glomerular filtration rate (eGFR) can differ according to whether serum creatinine (SCr) or cystatin C (Cys) is used for eGFR calculation, but the impact of these differences on adverse events of patients with cancer has not been demonstrated. We aimed to evaluate the impact of eGFR differences (eGFRdiff) between cystatin C–based eGFR (eGFRcys) and creatinine-based eGFR (eGFRcr) on the overall survival (OS) of patients with cancer.

Methods

This is a prospective cohort of adult patients with solid tumors (diagnosed in the last 90 days) initiating treatment at a Brazilian cancer center. eGFRcr and eGFRcys were calculated using the 2021 CKD-EPI equations. eGFRdiff was calculated: (eGFRcys-eGFRcr)*eGFRcr/100); If negative, eGFRcys < eGFRcr. SCr and Scys were measured through assays at the University of Minnesota in the same day of measured GFR (mGFR), determined by the plasma clearance of ⁵¹Cr-EDTA.

Results

A group of 1,011 patients recruited from April 2015 to September 2017 was included for analysis and censored in March 2023. Patients were 50.6 ±13 y, 50.7% female. The most common cancer sites were breast (22.4%), gastrointestinal (21.9%), and male genital (21.2%); 15.5% had metastasis. ECOG 0 & 1comprised 96%of patients. Time of follow-up was 5.7 (2.5-6.5) y; overall mortality was 27.4%. Mean mGFR was 79 ± 21 ml/min/1.73m2; 17.2% had mGFR <60ml/min/1.73m2. eGFRcr, eGFRcys, and eGFRcr-cys were 89.5 ± 19.9, 75.3 ± 23.8, and 84.2 ± 22.2 ml/min/1.73m2, respectively. eGFRdiff was lower than -30% in 22.5%, between -30 and +30% in 76.7%, and higher than+30% in 0.8% of patients. In the Cox regression model adjusted for age, sex, cancer site, metastasis, ECOG, and C-reactive protein, eGFRdiff lower than -30% was an independent predictor of reduced OS, even when adjusted for mGFR (Table).

Conclusion

This is the first study assessing the impact of eGFRdiff on the prognosis of patients with solid tumors. eGFRcys at least 30% lower than eGFRcr was associated with reduced OS. Our results endorse the utility of eGFRdiff as a predictor of worse outcomes in patients with cancer.

Funding

• Government Support – Non-U.S.