Significance of Body Surface Area Correction for Cisplatin Eligibility Based on Renal Function of Patients With Muscle-Invasive Bladder Cancer.

Introduction: Creatinine clearance (CCr) ≥60 mL/min without body surface area (BSA) correction is commonly applied to determine the cisplatin (CDDP) eligibility of patients with bladder cancer. However, since CDDP dosages are calculated according to BSA, there is concern that applying renal function without BSA correction may underestimate CDDP eligibility, especially of patients with low BSA. The purpose of this study was to determine whether BSA correction for renal function affects the decision of CDDP eligibility and oncological outcomes.

Patients And Methods: The data of 294 patients who received platinum-based neoadjuvant chemotherapy (NAC) and underwent radical cystectomy for muscle-invasive bladder cancer were retrospectively analyzed. Patients with BSA below and above the median BSA value (1.70 m) were divided into low-BSA and high-BSA groups. Patients who received ≥20% dose reduction of CDDP or replacement by carboplatin at the first NAC cycle were categorized as "inadequate-CDDP" recipients. "CDDP-eligibility underestimation" was defined as CCr with BSA correction >60 mL/min/1.73 m2 while CCr without BSA correction <60 mL/min. The association of BSA with inadequate-CDDP was evaluated using multivariate analysis. Additionally, differences in clinical outcomes, namely cancer-specific survival (CSS) and objective response rate (ORR) to NAC, between the low- and high-BSA groups were evaluated.

Results: CDDP-eligibility underestimation was more frequent in the low-BSA group than in the high-BSA group (17% vs. 0%; P < .001). Multivariate analysis revealed that low-BSA was independently associated with the risk of inadequate CDDP (odds ratio, 2.07; P = .012). CSS from initiation of NAC was significantly shorter in the low-BSA group than in the high-BSA group (hazard ratio, 2.24; P = .002). The ORR for NAC was also significantly lower in the low-BSA group (40.8% vs. 57.1%; P = .007).

Conclusions: When determining CDDP eligibility for renal function in patients with low BSA, renal function values corrected by standard BSA should be applied to prevent inappropriate dosing reductions.