Validation of the eighth edition of the American Joint Committee on Cancer staging system for ampulla of Vater cancer.

BACKGROUND: The American Joint Committee on Cancer recently proposed the eighth edition of cancer staging system. Validation studies are required to evaluate the prognostic stratification of ampulla of Vater cancer patients.

METHODS: In the study, 369 operatively resected patients with ampullary cancers were grouped based on the eighth T (T1a, limited to sphincter of Oddi; T1b, invasion to duodenal submucosa; T2, invasion to duodenal proper muscle; T3a, invasion to pancreas ≤0.5 cm; T3b, invasion to pancreas >0.5 cm; and T4, involvement of celiac axis or superior mesenteric artery) and N (N0, no nodal metastasis; N1, 1-3 nodal metastasis; and N2, ≥4 nodal metastasis) category of ampullary cancer staging.

RESULTS: Overall 5-year survival rates for T and N categories were as followed: T1a, 83%; T1b, 71%; T2, 46%; T3a, 48%; T3b, 28.5%, T4, 7% (P< .001); N0, 44.8%; N1, 20%; N2, 4% (P < .001). Pair-wise comparisons demonstrated significant differences between T1a-b (P = .005), T3a-T3b (P = .03), N0-N1 (P < .001), and N1-N2 (P = .007) tumors, but not between T1b-T2 (P = .20), T2-T3a (P = .84), and T3b-T4 (P = .17) lesions.

CONCLUSION: The eighth edition T category for ampullary cancer does not stratify patients accurately with regard to prognosis. Modification of the current T category with eliminating subcategories (T1, invasion to duodenal submucosa; T2, invasion to duodenal proper muscle; T3, invasion to pancreas or duodenal subserosa) is a better way for determining prognosis of ampullary cancer. The current N category segregates patient survival well.