Recommendations for the assessment of glomerular filtration rate in patients with cancer: A position statement and systematic review on behalf of the American Society of Onco-Nephrology (ASON).
Authors: Kitchlu Abhijat , Costa E Silva Veronica Torres , Anand Shuchi , Kala Jaya , Abudayyeh Ala , Inker Lesley , Liu Geoffrey , Leung Nelson , Herrmann Sandra M ,   ASON Position Statement Committee
Published: June 2024

e24143 Background: Accurate assessment of glomerular filtration rate (GFR) is crucial to guiding drug eligibility, dose-adjusting systemic therapy, and minimizing the risks of both undertreatment and toxicity in patients with cancer. To date, there has been a lack of guidance to standardize approaches to GFR estimation in the cancer population based on the available evidence. We aim to present data on the first systematic review (SR) of GFR estimating equations in patients with cancer. Methods: We conducted a SR on behalf of the American Society of Onco-Nephrology (ASON) on the accuracy of equations to estimate GFR in adult patients with cancer, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We required that studies use a reference methodology as comparator involving measured GFR via urinary or plasma clearance of an exogenous filtration marker or carboplatin. Two search strategies focusing on studies using serum creatinine (Cr) and cystatin C (Cys) were developed. Risk of bias and quality assessment was performed for all studies. Results: A total of 39 studies (21,949 patients in total, 19,025 with solid cancers) were included. Studies assessing populations in Europe were most frequent (50%), followed by Asia (27%) and the remaining from Australia/New Zealand and North and South America. Risk of bias and quality assessment allocated 15 studies (38%) as low or very low quality, and 24 (62%) as low-moderate or moderate quality. The most commonly assessed GFR estimating equations included Cockroft-Gault (32 studies), Modification of Diet Renal Disease (MDRD) (24 studies), Chronic Kidney Disese Epidemiology Collaboration Study (CKD-EPI)Cr (22 studies), Wright (13 studies), CKD-EPICys (8 studies), CKD-EPICr-Cys (8 studies), and Jeliffe (8 studies). Given the importance of accurate and timely eGFR assessment and the evidence supporting the performance (i.e., accuracy) of the CKD-EPI incorporating both Cr and Cys, we suggest the use of this equation in patients with cancer (grade 2C). Where Cys is unavailable, CKD-EPICr is the next preferred equation given the supporting data for its performance and widespread availability. Since included studies were moderate quality or lower, the ASON rated the certainty of evidence as low. Also, additional data on clinical outcomes related to the selection of eGFR equations is needed. We suggest measurement of GFR via an exogenous filtration marker in patients with cancer for whom eGFR results in borderline eligibility for therapies or clinical trials (ungraded). Conclusions: Based on the results of this SR, we suggest use of contemporary methods for estimation of GFR (CKD-EPICr-Cys and CKD-EPICr-Cr) and avoidance of older and less accurate formulae such as Cockcroft-Gault.