Initial adjustments in the dosage and rest period of gemcitabine plus cisplatin therapy for patients with incurable biliary tract cancer based on baseline estimated glomerular filtration rate (eGFR) values may be crucial for treatment outcomes and the preservation of renal function.

Background: Gemcitabine (GEM) and cisplatin (CDDP) combination therapy (GC therapy) is the standard 1st-line regimen for incurable biliary tract cancers (BTCs). However, the correlation between dynamic changes in renal function and the outcomes of GC therapy remains unclear. This study aimed to clarify the association between renal function alterations and treatment outcomes after GC therapy.

Methods: We retrospectively examined 44 patients with incurable BTC who underwent GC therapy (January 2015 to December 2022). The patients were stratified according to their baseline estimated glomerular filtration rate (eGFR). Changes in eGFR, overall survival (OS), and progression-free survival (PFS).

Results: The median baseline eGFRs were 65.0 mL/min/1.73 m² (low group, n=22) and 90.7 mL/min/1.73 m² (high group, n=22). No significant background differences were observed between the groups. During the 1st course, 86.4% and 54.5% of patients in the low and high groups underwent dose adjustments and/or administration postponement, which was found to be significantly greater in the low group. In the high group, eGFR decreased with an increase in the CDDP dose (100 mg =-12.0, 200 mg =-12.7, 300 mg =-25.9, and 400 mg =-25.7 mL/min/1.73 m²). In the low group, eGFR remained stable (100 mg =0.8, 200 mg =7.5, 300 mg =4.5, and 400 mg =-0.3 mL/min/1.73 m²). The decrease in the eGFR in the high group was significantly greater at each CDDP dose. However, the median OS and PFS were longer in the low group (OS: 16.3 vs. 9.2 months, P=0.02; PFS: 5.4 vs. 3.6 months, P=0.02). No significant differences in adverse events were observed between the groups.

Conclusions: Adjusting GC therapy based on baseline estimated glomerular eGFR may be pivotal for therapeutic benefits and renal function protection in patients with incurable BTC.