Estimation of Kidney Function in Oncology Implications for Anticancer Drug Selection and Dosing

Estimation of kidney function in patients with cancer directly affects drug dosing, agent selection, and eligibility for clinical trials of novel agents. Overestimation of kidney function may lead to overdosing or inappropriate agent selection and corresponding toxicity. Conversely, underestimation of kidney function may lead to underdosing or inappropriate agent exclusion and subsequent therapeutic failure. It would seem obvious that the most accurate estimates of kidney function should be used to reduce variability in decision making and ultimately, the therapeutic outcomes of toxicity and clinical benefit. However, clinical decision making is often more complex. The Cockcroft-Gault formula remains the most universally implemented estimator of kidney function in patients with cancer, despite its relative inaccuracy compared with the Chronic Kidney Disease Epidemiology Collaboration equation. The Chronic Kidney Disease Epidemiology Collaboration equation is a more precise estimator of kidney function; however, many currently used kidney function cutoff values were determined before the development of the Chronic Kidney Disease Epidemiology Collaboration equation and creatinine assay standardization using Cockcroft-Gault estimates. There is a need for additional studies investigating the validity of currently used estimates of kidney function in patients with cancer and the applicability of traditional anticancer dosing and eligibility guidelines to modern and more accurate estimates of kidney function. In this review, we consider contemporary calculation methods used to estimate kidney function in patients with cancer. We discuss the clinical implications of using these various methods, including the potential influence on drug dosing, drug selection, and clinical trial eligibility, using carboplatin and cisplatin as case studies.