Evaluating the prognostic significance of lymph node yield in resected pancreatic adenocarcinoma: a population-based study

INTRODUCTION: Surgical resection plays a pivotal role in the management of pancreatic cancer by achieving complete tumor removal and regional lymphadenectomy. Although most clinical guidelines recommend examining at least 15 lymph nodes for accurate staging and better prognostic assessment, the optimal threshold remains uncertain and requires validation across population-based datasets. METHODS: Using the Taiwan Cancer Registry and National Health Insurance Research Database, 885 patients with pancreatic adenocarcinoma who underwent curative resection between 2013 and 2019 were identified. Cox proportional hazards regression models were used to evaluate the association between lymph node yield (LNY ≥ 15 vs. <15) and overall survival (OS), adjusting for potential confounders. Several sensitivity analyses were performed to assess the robustness of the findings, including a subgroup analysis restricted to patients with pT1-3 pancreatic head tumors who underwent pancreatoduodenectomy. Stratified analyses were additionally performed according to pathological T and N classifications and treatment modalities. RESULTS: The median LNY was 15, with 474 patients (53.6%) having ≥ 15 nodes retrieved. Patients with adequate LNY were more likely to have tumors located in the pancreatic head, undergo pancreatoduodenectomy, and present with more advanced pT and pN stages as well as a higher number of positive nodes. No significant difference in 1- or 3-year overall survival (OS) was observed between patients with LNY ≥ 15 and those with LNY < 15 in the overall cohort. In the predefined subgroup of patients with pT1-3 pancreatic head tumors undergoing pancreatoduodenectomy, however, retrieval of ≥ 15 lymph nodes was associated with significantly improved 1- and 3-year OS compared with retrieval of < 15 lymph nodes. After adjustment for confounders, LNY ≥ 15 remained associated with improved 1- and 3-year OS in this subgroup, whereas no such association was observed in the overall cohort. Stratified analyses by pathological stage and treatment demonstrated generally consistent findings, with the most pronounced survival benefit of LNY ≥ 15 observed among patients with pT1-2 disease. CONCLUSIONS: Retrieval of ≥ 15 lymph nodes were not directly associated with improved survival in the overall cohort but was associated with better survival among patients with pT1-3 pancreatic head tumors undergoing pancreatoduodenectomy. These findings suggest that the prognostic value of the conventional 15-node threshold may vary across clinical subgroups and warrants further validation in larger population-based studies.