Formulas calculating creatinine clearance are inadequate for determining eligibility for cisplatin-based chemotherapy in bladder cancer

Abstract

Purpose: Efficacy of formulas calculating creatinine clearance (CrCl) to determine renal function eligibility (CrCl > 60 mL/min) for cisplatin-based chemotherapy has not been examined adequately in the bladder cancer population. We hypothesize these formulas may underestimate measured CrCl, and therefore the eligibility for cisplatin-based chemotherapy. Patients and Methods: A database of 208 patients with unresectable or metastatic bladder cancer treated on protocol at Memorial Sloan-Kettering Cancer Center (New York, NY) with cisplatin-based chemotherapy between 1983 and 1994 was examined retrospectively. The association between measured and calculated CrCl and the ability to complete three cycles (minimum therapeutic) of chemotherapy was examined. Results: Baseline measured CrCl was less than 60 mL/min in 16% compared with 12% to 44% using various formulas. Concordance between calculated and measured CrCl less than 60 mL/min was poor (range of κ, 0.14 to 0.38). In patients older than age 65, 22% had a measured CrCl less than 60 mL/min, compared with 10% to 63% calculated using various formulas. Overall, 80% completed at least three cycles of cisplatin-based chemotherapy. The ability to complete at least three cycles was statistically significantly related with a measured CrCl more than 60 mL/min (P = .02), but not with calculated CrCl more than 60 mL/min. Conclusion: Current formulas estimating CrCl tend to underestimate measured CrCl, especially in those older than 65 years. Depending on the formula used, up to 44% who actually received cisplatin-based chemotherapy based on measured CrCl would be deemed ineligible at present, potentially affecting survival outcomes. Methodology for determining CrCl and/or renal eligibility for cisplatin-based chemotherapy in patients with bladder cancer should be re-examined. © 2006 by American Society of Clinical Oncology.