Can estimated glomerular filtration rate (eGFR) replace isotopic measurement of GFR for carboplatin dosing in stage 1 seminoma

2589 Background: Accurate determination of GFR is essential for correct dosing of carboplatin, the standard adjuvant therapy for stage 1 seminoma. Isotopic methods (e.g. 51Cr-EDTA) remain the gold standard for determination of GFR. However, the use of eGFR could reduce the need for such isotope studies. As novel formulae to estimate GFR such as CKD-EPI and MDRD4 have improved the assessment of renal function in non-oncological settings, we investigated their utility for carboplatin dosing. Methods: 115 patients (pts) (mean age 40.3, std dev. 10.1) who received adjuvant carboplatin for stage 1 seminoma at our institution between 2007-2012 were identified. All pts underwent 51Cr-EDTA measurement of GFR with carboplatin dose calculated using the Calvert formula, based on GFR uncorrected for body surface area (BSA). Theoretical carboplatin doses were then calculated using eGFR values obtained using the CKD-EPI and MDRD4 formulae with additional calculation to uncorrect for BSA. Creatinine clearance was calcul...