Importance of Nodal Metastases Location in Pancreatoduodenectomy for Pancreatic Ductal Adenocarcinoma: Results from a Prospective, Lymphadenectomy Protocol

Background: Implementing a prospective lymphadenectomy protocol, we investigated the nodal yields and metastases per anatomical stations and nodal echelon following upfront pancreatoduodenectomy (PD) for cancer. Next, the relationship between the extension of nodal dissection, the number of examined and positive nodes (ELN/PLN), disease staging and prognosis was assessed. Methods: Lymphadenectomy included stations 5, 6, 8a-p, 12a-b-p, 13, 14a-b, 17, and jejunal mesentery nodes. Data were stratified by N-status, anatomical stations, and nodal echelons. First echelon was defined as stations embedded in the main specimen and second echelon as stations sampled as separate specimens. Recurrence and survival analyses were performed by using standard statistics. Results: Overall, 424 patients were enrolled from June 2013 through December 2018. The median number of ELN and PLN was 42 (interquartile range [IQR] 34-50) and 4 (IQR 2-8). Node-positive patients were 88.2%. The commonest metastatic sites were stations 13 (77.8%) and 14 (57.5%). The median number of ELN and PLN in the first echelon was 28 (IQR 23-34) and 4 (IQR 1-7). While first-echelon dissection provided enough ELN for optimal nodal staging, the aggregate rate of second-echelon metastases approached 30%. Nodal-related factors associated with recurrence and survival were N-status, multiple metastatic stations, metastases to station 14, and jejunal mesentery nodes. Conclusions: First-echelon dissection provides adequate number of ELN for optimal staging. Nodal metastases occur mostly at stations 13/14, although second-echelon involvement is frequent. Only station 14 and jejunal mesentery nodes involvement was prognostically relevant. This latter station should be included in the standard nodal map and analyzed pathologically.