Evaluation of AJCC Nodal Staging for Intraductal Papillary Mucinous Neoplasm-Derived Pancreatic Ductal Adenocarcinoma.

[BACKGROUND] The American Joint Committee on Cancer (AJCC) eighth edition is based on pancreatic intraepithelial neoplasia-derived pancreatic ductal adenocarcinoma (PDAC), a biologically distinct entity from intraductal papillary mucinous neoplasm (IPMN)-derived pancreatic cancer. The role of nodal disease and the AJCC's prognostic utility for IPMN-derived pancreatic cancer are unclear. This study aimed to evaluate the prognostic role of nodal disease and the AJCC eighth-edition N-staging for IPMN-derived pancreatic cancer.

[METHODS] Upfront-surgery patients with IPMN-derived PDAC from four centers were stratified according to the AJCC eighth-edition N stage. Disease characteristics were compared using descriptive statistics, and both overall survival (OS) and recurrence-free survival (RFS) were evaluated using log-rank tests. Multivariable Cox regression was performed to determine the prognostic value of N stage for OS, presented as hazard ratios with 95 % confidence intervals (95 % CIs). A lowest p value log-rank statistic was used to derive the optimal cutoff for node-positive disease.

[RESULTS] For 360 patients, advanced N stage was associated with worse T stage, grade, tubular histology, and perineural and lymphovascular invasion (all p < 0.05). The median OS was 98.3 months (95 % CI 82.8-122.0 months) for N0 disease, 27.8 months (95 % CI 24.4-41.7 months) for N1 disease, and 18.1 months (95 % CI 16.2-25.9 months) for N2 disease (p < 0.001). The AJCC N stage was validated and associated with worse OS (N1 [HR 1.64; range, 1.05-2.57], N2 [HR2.42; range, 1.48-3.96]) and RFS (N1 [HR 1.81; range, 1.23-2.68], N2 [HR 3.72; range, 2.40-5.77]). The optimal cutoff for positive nodes was five nodes.

[CONCLUSION] The AJCC eighth-edition N-staging is valid and prognostic for both OS and RFS in IPMN-derived PDAC.