Survival Outcomes of Gemcitabine Plus S-1 Adjuvant Chemotherapy after Surgical Resection for Advanced Biliary Tract Cancer.

INTRODUCTION The usefulness of adjuvant chemotherapy in biliary tract cancer (BTC) is poorly reported. This study aimed to evaluate the effectiveness and safety of adjuvant gemcitabine plus S-1 (GS) chemotherapy after curative surgical resection for BTC. METHODS 225 BTC patients who underwent surgical resection between January 2006 and May 2019 were enrolled in this study. Twenty-seven patients received adjuvant chemotherapy with GS (GS group), whereas 67 patients underwent surgery alone (S group). Twenty-three matching pairs were derived through propensity score (PS) matching analysis. Patients received 12 cycles of adjuvant chemotherapy (70 mg/m2 oral S-1 for 7 consecutive days plus intravenous gemcitabine 1,000 mg/m2 on day 7). The primary end point was recurrence-free survival (RFS). The secondary end points were the 1-, 2-, and 3-year RFS and overall survival (OS) rates, tolerability, and frequency of grade 3/4 toxicity. RESULTS The completion rate was 81.5%; no treatment-related deaths were observed. Grade 3/4 adverse events were seen in 40.7% of the patients. RFS (3-year RFS rate: 59.3% vs. 39.1%, p = 0.049) and OS (3-year OS rate: 71.7% vs. 53.4%, p = 0.008) were significantly better in the GS group than in the S group among PS-matched pairs. DISCUSSION/CONCLUSION GS chemotherapy after curative surgery was well tolerated, showed better clinical benefit in the adjuvant setting, and can effectively reduce BTC recurrence.