Background: Nodal staging systems (NSS) for pancreatic ductal adenocarcinoma (PDAC) classify patients on the basis of number of metastatic lymph nodes (MLN), metastatic/retrieved lymph node ratio (LNR), and log odds of positive LN (LODDS). The relative prognostic performance of these NSS, however, remains unclear.
Patients and methods: We identified 2584 patients who underwent surgery for PDAC between 2010 and 2019. Subgroups of each staging system were classified using K-adaptive partitioning method and assessed by comparing time-dependent areas under the curve (AUC) 5 years after surgery.
Results: Patients were subgrouped by MLN (0, 1-3, ≥ 4), LNR (0, 0-0.23, > 0.23), and LODDS (< - 3.5, - 3.5 to - 0.970, > - 0.97). All three NSS were independent prognostic factors for overall survival (OS) and recurrence-free survival (RFS). The AUCs for OS were comparable for the MLN (0.622), LNR (0.609), and LODDS (0.596) systems. Subgroup evaluation based on 12 retrieved lymph nodes (RLN), R1 resection, and extent of resection showed that the AUCs of the MLN and LNR NSS were comparable for OS and RFS regardless of the number of RLNs, R1 resection, and extent of resection. By contrast, the AUCs of the LODDS NSS were lower.
Conclusion: The NSS based on the number of MLN is the best prognostic indicator, with prognostic performance comparable to the other NSS and greater convenience for practical use. This NSS was applicable regardless of the numbers of RLN, R1 resection, and extent of resection.
© 2021. Society of Surgical Oncology.