Impact of tumor size  in predicting outcome in patients with ampullary cancer

Purpose : Periampullary, pancreatic ductal, distal bile duct and duodenal carcinomas have overlapping gross presentation and morphology. Exact site of origin is often difficult to establish conclusively, yet they have differing AJCC TNM staging systems. This makes grossing Whipple’s specimens daunting in centers with limited volume, increasing the chance of inaccurate staging. The aim of this study is to validate an alternative size-based staging system for ampullary cancers, using pancreatic ductal adenocarcinoma staging characteristics, which can simplify pathological assessment of Whipple’s specimens. Methods : Clinicopathologic data from all consecutive patients of ampullary adenocarcinoma were retrospectively reviewed. Prognostic correlation of this alternative size-based staging system (using cut-offs of 2 and 4cm) was done with disease free survival (DFS) and overall survival (OS). This alternative staging proposal was compared with the current AJCC8 tumour staging system and other histological prognostic parameters. Results : After applying exclusion criteria, 146 cases were analyzed in this study. The tumor size-based stage did not correlate significantly with DFS (p=0.4) or OS (p=0.3), but the AJCC8 T stage did (p=0.03). Multivariate analysis using both AJCC T stage and size-based categorization, also did not show any prognostic correlation with outcome, though positive surgical margins, perineural invasion and the pN2 nodal status were established as independent prognostic factors. Conclusions : Tumor size-based staging (using pancreatic ductal cancer criteria) is currently inferior to AJCC TNM stage for ampullary carcinoma and needs further evaluation in large multi-institutional studies.