Choosing the Platinum Partner in Advanced Biliary Tract Cancer: A Propensity Score-Matched Real-World Comparison of Gemcitabine Plus Carboplatin Versus Gemcitabine Plus Cisplatin.

Gemcitabine plus cisplatin (GemCis) has been served as an important first-line chemotherapy backbone for unresectable locally advanced or metastatic biliary tract cancer (BTC). However, cisplatin is unsuitable for all patients. Gemcitabine plus carboplatin (GemCarbo) is frequently used as an alternative, but direct comparative data remain limited. We retrospectively review patients with unresectable locally advanced or metastatic BTC who received first-line GemCis or GemCarbo at Songklanagarind Hospital between 2011 and 2025. The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and selected laboratory-based safety outcomes. Propensity score matching was applied to reduce baseline treatment selection bias. Among 154 eligible patients, 95 received GemCis and 59 received GemCarbo. In the overall cohort, median OS was 8.44 months with GemCarbo and 9.82 months with GemCis (HR, 1.18; 95% CI, 0.82-1.70; p = 0.382). After propensity score matching, median OS was 8.44 months with GemCarbo and 11.63 months with GemCis (HR, 1.26; 95% CI, 0.84-1.90; p = 0.271). Median PFS was 4.27 and 5.75 months (HR, 0.91; 95% CI, 0.62-1.33; p = 0.617). ORR and DCR were comparable among evaluable patients. Increased serum creatinine was more frequent with GemCis, whereas hematologic toxicities were comparable. GemCarbo showed no statistically significant difference in OS or PFS compared with GemCis, suggesting that it may be considered as an alternative when cisplatin is unsuitable. However, prospective validation is warranted.