Impact of Adjusted Creatinine Clearance on Carboplatin Dosing in Endometrial Cancer: A Retrospective Study

Carboplatin (CBDCA) dosing is commonly determined using the Calvert formula, with creatinine clearance (Ccr) estimated by the Cockcroft-Gault formula. In Japan, where serum creatinine (sCr) is usually measured enzymatically, unadjusted Ccr may overestimate glomerular filtration rate and lead to CBDCA overdosing. We retrospectively compared treatment exposure, hematologic toxicity, and exploratory oncologic outcomes in patients with endometrial cancer who received postoperative paclitaxel plus CBDCA therapy. Patients were grouped according to whether CBDCA dosing was based on the conventional Cockcroft-Gault formula (CG group) or on adjusted Ccr calculated by adding 0.2 mg/dL to sCr (adjusted group). The incidence of Grade ≥3 neutropenia was significantly lower in the adjusted group than in the CG group. The 5-year progression-free survival (PFS) rate was numerically lower in the adjusted group than in the CG group, although no statistically significant difference was observed between the groups. Because the number of PFS events was limited, the effect of adjusted Ccr-based dosing on oncologic outcomes remains uncertain. These findings suggest that adjusted Ccr-based dosing may reduce hematologic toxicity in routine clinical practice. However, given the limited number of PFS events and the wide uncertainty in survival estimates, further studies are needed to clarify its impact on oncologic outcomes.