Prognostic Relevance of Number and Ratio of Metastatic Lymph Nodes in Resected Pancreatic, Ampullary, and Distal Bile Duct Carcinomas

Background: Lymph node ratio (LNR) may be more useful than nodal (N) status in prognostic subclassification of adenocarcinomas after pancreatoduodenectomy. Ampullary (AC), biliary (DBC), and pancreatic (PC) adenocarcinomas are biologically distinct, and nodal involvement may have different prognostic importance among these separate cancers.

Methods: We included 179 consecutive pancreatoduodenectomies for PC, AC, or DBC, and performed standardized histopathologic evaluation, including prospective registration and retrospective reevaluation of the cancer origin. Associations between histopathologic variables and LNR, N status, and number of metastatic nodes were evaluated. Unadjusted and adjusted survival analysis was performed.

Results: Overall 5 year survival was 6% for PC (n=72), 26% for DBC (n=46), and 46% for AC (n=61). Lymph node involvement was more frequent in PC (75%) than in AC (48%) and DBC (57%). In PC, N status did not discriminate between prognostic groups (N1 vs. N0; p=0.31). However, increasing LNR was associated with poorer survival in unadjusted analysis, as well as when adjusting for margin involvement, degree of differentiation, and tumor diameter (p=0.032; hazard ratio 1.87, 95% confidence interval 1.06-3.31). In AC and DBC, N status clearly discriminated between subgroups of patients with different long-term survival in unadjusted and adjusted survival analysis (N1 vs. N0; p<0.001), whereas number of metastatic nodes and LNR did not predict survival among node-positive resections.

Conclusions: The predictive value of nodal involvement depends on the type of cancer within the pancreatic head. In AC and DBC, N status adequately discriminates between good and poor prognosis. In PC, LNR may be more powerful in prognostic subclassification.