Proposed new staging system for ampulla of Vater cancer with greater discriminatory ability: multinational study from eastern and western centers

Background We built a multinational retrospective database of patients with ampulla of Vater cancer to develop a reliable new staging system. Method This study included 841 patients with ampulla of Vater cancer after curative surgery at Seoul National University Hospital ( n  = 440) and Johns Hopkins University medical institutions ( n  = 401) between 1985 and 2013. Results The 5‐year overall survival ( OS ) rates of patients staged according to the 7 th American Joint Committee on Cancer staging system were 80.3%, 60.9%, 58.1%, 36.6%, 17.9%, and 25.0% for Stages IA ( n  = 140), IB ( n  = 194), IIA ( n  = 115), IIB ( n  = 348), III ( n  = 33), and IV ( n  = 4), respectively. Five‐year OS rates were similar in patients with Stage IB (T2N0M0) and IIA (T3N0M0) tumors ( P  = 0.556), but differed significantly between other pairs of groups. The number of positive lymph nodes ( PLN ) enhanced prognosis when stratified as 0, 1–2 and ≥3 ( P  < 0.001). The revised staging system consisted of Stages I (T1, PLN 0), IIA (T2–T3, PLN 0), IIB (T1–T3, PLN 1–2), III ( PLN ≥3 or any T4), and IV (any M1), with 5‐year OS rates differing significantly in each pair of groups, including Stages I and IIA ( P  < 0.001). Conclusion This new staging system has better discriminatory ability in stratifying 5‐year OS rates based on a large multinational database.