Carboplatin clearance is correlated with Glomerular Filtration Rate (GFR), which is usually evaluated with creatinine clearance using Cockcroft-Gault (CG) formula. Because serum creatinine (sCR) level is related to total muscle mass, we hypothesized that an abnormal body composition with a low lean body mass (LBM) percentage (LBM / weight) may result in GFR overestimation and inadequate carboplatin dose calculation by using CG formula. Serum cystatin C (sCY) is an alternative marker of GFR which is not affected by muscle mass. We aimed to correlate GFR creatinine (GFRCr) and cystatin C (GFRCy) to LBM percentage and the risk of toxicity. A high GFRCr/GFRCy ratio might estimate the miscalculation of GFR with sCR.
sCR and sCY were prospectively measured in consecutive cancer patients (pts) before chemotherapy. GFRCr and GFRCy were calculated with CG and GRUBB formula, respectively. The LBM was assessed using CT-scan. Febrile neutropenia and grade 3-4 thrombocytopenia were analysed in a subgroup of pts treated with carboplatin AUC 5 +/- paclitaxel.
In 134 cancer pts (males 51%), median age was 63.7 (20 – 89). In 128 pts without severe renal insufficiency, sCR was correlated with LBM (r = 0.30, Pearson correlation coefficient, p 1.4.
Pts with a low LBM percentage (sarcopenic overweight pts) are at high risk of inadequate calculation of renal function, over dosage of carboplatin and increased acute limiting toxicity. High GFRCr/GFRCy ratio allows to identify these pts.
Clinical trial identification
Legal entity responsible for the study
Fondation Martine Midy
All authors have declared no conflicts of interest.