Glomerular filtration rate (GFR) in patients with stage I testicular seminoma treated with adjuvant carboplatin: A comparison of six formulae compared to a radioisotope gold standard

Abstract

15504 Background: Carboplatin (Carbo) is an effective adjuvant treatment for patients (pts) with stage I testicular seminoma. Accurate estimation of GFR is necessary to establish carbo dose. Calculation of GFR following injection of a radiolabelled isotope (e.g. Tc99mDTPA) is considered the gold standard, but may not be readily available in all centres. Calculation of creatinine clearence via 24-h urine collection is often unreliable. The aim of this study was to assess different formulae for GFR calculation in this patient population. Methods: We performed a retrospective analysis of all patients with stage I seminoma treated with adjuvant carbo in Southampton between 1999 and 2005. All patients underwent GFR measurement with Tc99mDTPA and this was compared with six standard formulae for the calculation of GFR based on serum creatinine. Bias was quantified by Mean Percentage Error (MPE %) and precision by Mean Absolute Percentage Error (MAPE%). Tc99mDTPA GFR was not corrected for body surface area (BSA). Results: 202 Caucasian male pts were included (mean age 40 yrs; mean Tc99mDTPA GFR 123ml/min). Results are illustrated in Table 1 . Conclusions: In general, formulae underestimate GFR leading to significant decreases in carbo dose. The Cockcroft-Gault and Martin formulae were most accurate in this cohort of pts. Formulae developed for use in pts with chronic kidney disease (MDRD), elderly cancer patients (Wright) or which correct for BSA (Jelliffe, MDRD, Mayo), greatly underestimate GFR and should not be used in this setting. [Table: see text] No significant financial relationships to disclose.

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