Ampullary adenocarcinoma: What is the best approach? Insights from a large retrospective series.

e16473 Background: Ampullary adenocarcinoma (AAC) is rare (~0.2% of gastrointestinal cancers), but is increasing in incidence. Knowledge about risk factors, diagnosis and optimal treatment of AAC is still limited. Methods: We conducteda retrospective analysis of patients (pts) diagnosed with AAC between January 2015 and December 2023. Baseline clinical and histopathological data were collected. We used a multivariable Cox regression model to test the prognostic impact of clinical and treatment-related variables. Results: A total of 106 pts were included with median age of 69 years (37–84), 58.5% (n = 62) male. ECOG performance status was ≤ 1 in 92.5% (n = 98) of cases. Localized disease was present in 96.2% (n = 102), with 28.3% (n = 30) stage I, 6.6% (n = 7) stage II, and 61.3% (n = 65) stage III. Adjuvant therapy was given to 47% (n = 48) of pts, with 39 pts receiving chemotherapy and 9 pts receiving chemoradiotherapy. Gemcitabine (n = 14) and capecitabine (n = 9) were the most used agents in adjuvant chemotherapy and chemoradiotherapy, respectively. Median follow-up was 29.3 months (1–114). Recurrence occurred in 26.5% (n = 27), with a median time to recurrence of 25.7 months (1-113). Median recurrence-free survival (mRFS) was not reached ([NR], NR-NR) for pts undergoing curative surgery at diagnosis. There was no statistical difference in mRFS between the intestinal and pancreatobiliary subtypes (hazard ratio [HR] 0.78, p = 0.54, 95% confidence interval (CI) 0.4-1.7). Factors associated with lower mRFS in localized disease included T3-4 tumors (HR 3.2, p = 0.003, 95%CI 1.4-7.1), N+ disease (HR 2.35, p = 0.031, 95%CI 1.1-5.3), lymphovascular invasion (LVI) (HR 2.45, p = 0.015, 95%CI 1.2-5.3),perineural invasion (PnI) (HR 2.9, p = 0.002, 95%CI 1.4-6.2), histological grade 3 (HR 2.7, p = 0.003, 95%CI 1.4-5.6), and R1 resection (HR 4.06, p < 0.001, 95%CI 1.9-8.9). Adjuvant therapy was not associated with a higher mRFS (HR 0.71, p = 0.35, 95%CI 0.4-1.5). Median overall survival (mOS) was not reached ([NR], NR-NR) for localized disease and was 13.6 (10.9-16.3) months for all-time stage IV disease, with 11.8 months for first line therapy and 5.9 months for second line. Worse mOS in pts with localized disease ab initio was associated with T3-T4 tumors (HR 3.28, p = 0.002, 95%CI 1.5-7.3), N+ disease (HR 2.4, p = 0.026, 95%CI 1.1-5.4), LVI and PnI (HR 2.7, p = 0.006, 95%CI 1.3-5.9 and HR 3.2, p < 0.001, 95%CI 1.5-6.6, respectively), histological grade 3 (HR 2.8, p = 0.003, 95%CI 1.3-5.7), R1 surgery (HR 3.4, p = 0.001, 95%CI 1.56-7.38). Conclusions: In this large series of pts diagnosed with AAC, adjuvant therapy did not seem to make a statistical difference in both mRFS and mOS. Size, N status, LVI, PnI, histological grade, and resection margin are significant prognostic factors and should guide treatment strategies. Further research is needed to optimize patient selection and treatment strategies for prognosis.