Extent of regional lymphadenectomy and number-based nodal classification for non-ampullary duodenal adenocarcinoma

Background: This study aimed to evaluate the adequate extent of regional lymphadenectomy according to tumor location and the impact of number-based nodal classification on survival in patients with non-ampullary duodenal adenocarcinoma (NADAC). Methods: A total of 85 patients with NADAC who underwent surgery were enrolled. The frequency of metastasis was calculated for each node group in the respective tumor locations for 63 patients who underwent lymphadenectomy for pT2-pT4 tumor. Results: The frequency of metastasis in the pancreaticoduodenal (nos. 13 and 17) and superior mesenteric artery (no. 14) nodes was high (16.7 %-52.3 %) regardless of tumor location. Metastasis in the perigastric (nos. 3 and 4d) and right celiac artery (no. 9) nodes was not uncommon (14.3 %-22.2 %) for tumors in the first portion. The frequency of metastasis in the pyloric (nos. 5 and 6) and the other peripancreaticoduodenal (nos. 8 and 12) nodes varied depending on tumor location but could not be ignored for staging. When these nodes were classified as regional nodes, the 5-year survival in patients with pN0, pN1 (1-2 positive nodes), and pN2 (>= 3 positive nodes) were 82.9 %, 51.7 %, and 19.2 %, respectively (p < 0.001). pN classification independently predicted survival (pN1, p = 0.022; pN2, p < 0.001). Conclusions: Nos. 5, 6, 8, 12, 13, 14, and 17 nodes in all advanced NADAC and nos. 3, 4d, and 9 nodes in advanced NADAC in the first portion should be considered as regional nodes for accurate staging. The numberbased nodal classification allows good patients' prognostic stratification.