Population-Based Cohort Study on Treatment and Overall Survival of Patients Clinically Diagnosed With T1 Ampullary Cancer.

Objective: To evaluate treatment outcomes, overall survival (OS), and prognostic factors for OS in patients diagnosed with T1 ampullary cancer.

Background: Ampullary cancer is a rare gastrointestinal malignancy with limited data from large cohorts, especially regarding T1 disease.

Methods: Patients diagnosed with clinical (c) T1 ampullary cancer and patients with pathological (p) T1 in the case of cTx were included from the Netherlands Cancer Registry (2014-2021). Primary endpoint was OS, analyzed using the Kaplan-Meier estimator. Multivariable Cox proportional hazards regression was used to identify OS predictors.

Results: Overall, 244 patients with cT1 ampullary cancer were included, of whom 75% (n=184) underwent resection. Among these, 68% (n=125) were upstaged to a higher pathologically T classification (pT2:40%, pT3:22%, pT4:5%). Similarly, cN0 was upstaged to pN1 in 47% of patients (n=87). Next, 100 patients with pT1 and cTx ampullary cancer were included, making a total of 159 patients with pT1 tumor. 92% (146/159) underwent pancreatoduodenectomy while 8% (13/159) underwent endoscopic or local surgical resection. The 1- and 5-year OS for cT1N0 ampullary cancer were 72% and 36%, while for pT1N0 they were 94% and 75%. Independent poor prognostic factors for OS were pN1 classification (HR 2.12; 95%CI 1.15-3.94, P =0.017), pNx classification (i.e. locally resected patients) (HR 2.82; 95%CI 1.22-6.55, P =0.016), and poorly differentiated tumors (HR 4.05; 95%CI 1.33-12.40, P =0.014).

Conclusion: In patients with cT1 ampullary cancer, more than two-thirds had a pathologically higher T classification, and almost half had a pathologically higher N classification. These findings suggest that pancreatoduodenectomy is recommended for cT1 ampullary cancer.