CA 19-9 Surveillance Detects Recurrences Early and Contributes to Improvement in Survival in Resected Ampullary Cancers: Analysis of 572 cases.

Objective: To determine the clinical utility of serum CA 19-9 surveillance for detecting recurrences in resected ampullary carcinomas (ACs).

Introduction: Although an established prognostic marker for pancreatic ductal adenocarcinoma, the value of CA 19-9 in resected ACs during follow-up is unknown.

Methods: Retrospective analysis of ACs undergoing pancreaticoduodenectomy at Tata Memorial Centre-Mumbai, from January 2012 to January 2020 was performed. Survival, recurrence patterns, factors associated with recurrences and the utility of CA 19-9 surveillance were assessed.

Results: The 5-year OS of 572 included patients with ACs, was 56.4%. There were 251(43.88%) recurrences, majority being distant (n=223). Higher 'T' & 'N' stage, margin involvement, perineural invasion, poor tumour differentiation and pancreatobiliary subtype were associated with poor outcomes. Optimal CA 19-9 level to predict recurrence was 77.85 U/mL (sensitivity-61.22%, specificity-76.67%, AUC-0.711); however, a serial rise was a more accurate predictor (sensitivity-71.05%, specificity-91.67%). The median duration between the first rise in CA 19-9 (>37 U/mL) and radiological evidence of recurrence was 4.04 months. The optimal level of relative rise in CA 19-9 in diagnosing a recurrence was established at 2.79x (sensitivity-46.26%, specificity-83.33%, AUC-0.614). A serial rise and absolute value of >200 U/mL was associated with recurrence in 87% & 92.9% of cases. Recurrence detection & treatment after serum CA 19-9 elevation was associated with superior median survival as compared to recurrence detection without elevation (12.8 mo vs. 7.6 mo, P=0.005).

Conclusion: Serum CA 19-9 testing during follow-up evaluation detects recurrences early and improves survival in resected ACs, and therefore should be recommended as a routine surveillance test.