Objective: The aim of this study was to investigate the clinical relevance of the 8th edition of the Union for International Cancer Control classification of TNM staging for ampulla of Vater carcinoma (AC).
Methods: A total of 104 consecutive patients who underwent macroscopic curative resection for AC between January 2002 and September 2017 were investigated.
Results: Significant differences in recurrence-free survival (RFS) were found between T1a and T1b (p = 0.0030), but not between T1b and T2 (p = 0.9319), T2 and T3a (p = 0.0732), or T3a and T3b (p = 0.2118). The prognostic impact of the depth of duodenal invasion and pancreatic invasion, which define the T category, were evaluated. With regard to duodenal invasion, significant differences in RFS were found between the negative and submucosa classifications (p = 0.0012) and the muscularis propria and serosa classifications (p = 0.0131), but not between the submucosa and muscularis propria classifications (p = 0.6390). With regard to pancreatic invasion, significant differences in RFS were found between the negative and ≤ 0.5 cm classifications (p = 0.0001), and ≤ 0.5 cm and > 0.5 cm classifications (p = 0.0062). A Cox proportional hazard analysis for RFS revealed that duodenal invasion (submucosa or muscularis propria/negative, hazard ratio [HR] 5.08; serosa/negative, HR 7.42), and pancreatic invasion (≤ 0.5 cm/negative, HR 8.23; > 0.5 cm/negative, HR 9.81) were independent prognostic factors. An alternative new T category was proposed, based on the HRs, as follows: T1, tumor limited to the ampulla of Vater or sphincter of Oddi; T2, duodenal invasion (submucosa or muscularis propria); T3, pancreatic invasion (≤ 0.5 cm) or duodenal invasion (serosa); and T4, pancreatic invasion (> 0.5 cm). This alternative T category can well classify each subgroup with prognostic differences.
Conclusions: Reconsideration of the T category based on the prognostic impact of TNM factors, including the depth of duodenal and pancreatic invasion, are required in the 8th edition T category.