Surgeons treating T1 ampullary cancer need to consider high upstaging rates and significant survival disparities based on pathologic classification.

• In this cohort of 244 T1 ampullary cancer patients, 75% underwent resection, but 68% were upstaged to higher T classifications post-surgery.
• Five-year overall survival rates were starkly different: 36% for clinical T1N0 vs. 75% for pathologic T1N0 patients.

Given these findings, pancreatoduodenectomy is recommended over local resection for better outcomes.

• Independent predictors for poor survival include pathologic N1 (HR: 2.12) and poorly differentiated tumors (HR: 4.05).