Efficacy Analysis of Adjuvant Chemotherapy with Gemcitabine Plus Platinum or S-1 in Biliary Tract Carcinoma: A Multi-Center Retrospective Study

Purpose Biliary tract cancers (BTCs) have a poor overall prognosis, as patients who underwent curative surgery frequently experience disease recurrence. At present, there is a paucity of well-documented adjuvant chemotherapy regimen. This study aimed to assess whether gemcitabine plus platinum or S-1 adjuvant chemotherapy have different impact on relapse-free survival (RFS). Patients and Methods We selected patients undergoing radical biliary tract cancer surgery, pathologically confirmed adenocarcinoma and received gemcitabine plus platinum (cisplatin or oxaliplatin) or S-1 adjuvant chemotherapy from September 2013 to May 2020. The primary study endpoint was RFS. The secondary endpoint was safety. Results Overall 136 patients were enrolled. The median follow-up was 32.3 months and the median RFS was 17.0 months (95% CI 8.9-25.1). The median RFS was 14.1 months (95% CI 6.7-21.5) in gemcitabine plus platinum group and 33.0 months (95% CI 9.3-56.7) in gemcitabine plus S-1 (GS) group, a non-significant difference both in univariate (P=0.092) and in multivariate analysis (P=0.058). Lymph node status (N- vs N+: HR=0.477, 95% CI 0.285-0.799; P=0.005) and chemotherapy cycles (<6 vs 6-8: HR=1.828, 95% CI 1.117-2.993; P=0.016) were independent impact factors for RFS. GS group had lower incidence of adverse reactions. Conclusion Compared with gemcitabine plus platinum, GS regimen has a tendency to obtain longer RFS (although there is no statistically significant difference) and less toxic. GS regimen has the potential to be investigated as a standard regimen for adjuvant chemotherapy.