Predictors of renal function decline during platinum-based chemotherapy in advanced urothelial carcinoma

Abstract Background Platinum-based chemotherapy remains the cornerstone treatment for advanced urothelial carcinoma (aUC). However, treatment selection is often influenced by baseline renal function. Gemcitabine plus carboplatin (GCa) is widely used in patients who are considered ineligible for cisplatin; however, whether GCa is intrinsically less nephrotoxic than cisplatin-based regimens remains unclear. This study evaluated the changes in renal function during chemotherapy using ΔeGFR and investigated the clinical factors associated with renal function decline. Methods We conducted a retrospective, single-center study of patients with aUC who received first-line gemcitabine plus cisplatin (GC) or GCa between 2014 and 2024. The primary endpoint was ΔeGFR, defined as the baseline eGFR minus the nadir eGFR during chemotherapy. Because renal parameters showed skewed distributions, non-parametric tests were used for group comparisons. Variables with p < 0.10 in univariable analyses were included in multivariable linear regression. Results A total of 86 patients were analyzed (GC, n = 66; GCa, n = 20). Patients in the GCa group were older and had significantly lower baseline eGFR than those in the GC group. The ΔeGFR distribution was smaller in the GCa group than in the GC group (Fig. 1). Baseline eGFR showed a strong positive correlation with ΔeGFR ( r = 0.794, p < 0.001; Fig. 2). In univariable analysis, regimen (GC vs. GCa: B = − 16.116, 95% CI − 23.317 to − 8.915, p < 0.001), baseline eGFR, hemoglobin, and corrected calcium were associated with ΔeGFR. However, in the multivariable analysis, only baseline eGFR remained independently associated with ΔeGFR (B = 0.523, 95% CI 0.396–0.650, p < 0.001). Conclusions Baseline renal function, rather than the choice of platinum regimen, was the principal factor associated with renal function decline during platinum-based chemotherapy in patients with advanced urothelial carcinoma. The smaller ΔeGFR observed in patients treated with GCa likely reflected treatment selection based on pre-existing renal impairment rather than reduced regimen-specific nephrotoxicity. These findings highlight the importance of baseline renal function assessment when selecting platinum-based chemotherapy and support the clinical feasibility of carboplatin-based treatment in patients with impaired renal function.