Reevaluation of regional lymph nodes in patients with pancreatic ductal adenocarcinoma in the pancreatic body and tail.

Introduction: In patients with pancreatic ductal adenocarcinoma (PDAC) in the pancreatic body (Pb) and tail (Pt), the appropriate area for lymphadenectomy is controversial. This study aimed to reevaluate the extent of lymph node (LN) metastasis in Pb- and Pt-PDAC, and to define the optimal area of LN dissection. Patients and methods: This single-center retrospective study evaluated patients with Pb- and Pt-PDAC who underwent distal pancreatectomy with extended lymphadenectomy between 2006 and 2020. LN metastasis in >3.0% of patients were defined as new regional LN. Results: The study cohort included 135 patients with Pb-PDAC and 42 patients with Pt-PDAC. In patients with Pb-PDAC, LNs around the splenic artery (SPA) had the highest metastasis-positive rate (54.1%). LNs along the left gastric artery, common hepatic artery, celiac axis (CA), superior mesenteric artery (SMA), and splenic hilus were defined as new regional LNs. In patients with Pt-PDAC, LNs at the splenic hilum had the highest metastasis-positive rate (38.1%). The station and LN around the SPA were defined as new regional LNs in those with Pt-PDAC. Metastasis beyond the newly defined regional LNs was not associated with survival. The incidence of LN metastasis was lower in patients who received preoperative chemotherapy than in those who underwent upfront surgery in both Pb- and Pt-PDAC. Conclusion: Although it needs to be verified in future multicenter studies, LN of both the CA and SMA systems should be dissected in patients with Pb-PDAC. However, only those around the SPA and splenic hilus should be dissected routinely in those with Pt-PDAC.