Evaluation of carboplatin toxicities and efficacy using different body weight descriptors in the Calvert formula.

Abstract

e14017 Background: Carboplatin dosing is calculated using the Calvert formula that includes glomerular filtration rate (GFR). In practice, GFR is often substituted by creatinine clearance (CrCl) with the Cockcroft-Gault (CG) equation. However, there is no standardization of which body weight descriptors should be utilized. Data suggest use of total body weight (TBW) may overestimate CrCl in overweight patients, while adjusted body weight may better estimate CrCl. The primary objective is to determine the impact of using different weight descriptors (DWD) in place of TBW for carboplatin dosing. Methods: This was a single-center, retrospective cohort study. Patients over 18 who were intended to receive at least 6 cycles of carboplatin with target area under the curve (AUC) of 5 or 6 and paclitaxel 175 to 225 mg/m2 were included. DWD included: adjusted body weight for overweight and obese patients, ideal body weight for normal weight patients and TBW for underweight patients. Primary endpoint was the composite of grade 3 or 4 anemia, thrombocytopenia and neutropenia (hematologic toxicity). Secondary endpoints included individual parameters of the primary endpoint, dose delays, dose reductions, progression-free survival, overall survival and objective response rate. Results: A total of 117 patients were included (DWD: n = 39; TBW: n = 78). Results on survival analysis, anemia and dose reductions are pending. Conclusions: To our knowledge, this is the first evaluation of patient outcomes specifically comparing carboplatin dosing calculations. Although there is a trend toward decreased grade 3 and 4 hematologic toxicities in the DWD group, there is no statistically significant difference in this under powered cohort. However, there was a significant decrease in treatment delays and days of treatment delay (p < 0.001) in the DWD group. Further studies are needed to evaluate the impact of DWD on carboplatin dosing. [Table: see text]