Outcomes of Palliative Chemotherapy for Ampulla of Vater Adenocarcinoma: A Multicenter Cohort Study.

Background/Aims: : Palliative chemotherapy (PC) is not standardized for patients with advanced ampulla of Vater adenocarcinoma (AA). This multicenter, retrospective study evaluated first-line PC outcomes in patients with AA. Methods: : Patients diagnosed with AA between January 2010 and December 2020 who underwent PC were enrolled from 10 institutions. Overall survival (OS) and progression-free survival (PFS) according to the chemotherapy regimen were analyzed. Results: : Of 255 patients (mean age, 64.0±10.0 years; male, 57.6%), 14 (5.5%) had locally advanced AA and 241 (94.5%) had metastatic AA. Gemcitabine plus cisplatin (GP) was administered as first-line chemotherapy to 192 patients (75.3%), whereas capecitabine plus oxaliplatin (CAPOX) was administered to 39 patients (15.3%). The median OS of all patients was 19.8 months (95% confidence interval [CI], 17.3 to 22.3), and that of patients who received GP and CAPOX was 20.4 months (95% CI, 17.2 to 23.6) and 16.0 months (95% CI, 11.2 to 20.7), respectively. The median PFS of GP and CAPOX patients were 8.4 months (95% CI, 7.1 to 9.7) and 5.1 months (95% CI, 2.5 to 7.8), respectively. PC for AA demonstrated improved median outcomes in both OS and PFS compared to conventional bile duct cancers that included AA. Conclusions: : While previous studies have shown mixed prognostic outcomes when AA was analyzed together with other biliary tract cancers, our study unveils a distinct clinical prognosis specific to AA on a large scale with systemic anticancer therapy. These findings suggest that AA is a distinct type of tumor, different from other biliary tract cancers, and AA itself could be expected to have a favorable response to PC.