The number and ratio of positive lymph nodes affect pancreatic cancer patient survival after neoadjuvant therapy and pancreaticoduodenectomy

Aims: This study is to examine the significance of the number and ratio of positive nodes in post-neoadjuvant therapy pancreaticoduodenectomy (PD) for pancreatic ductal adenocarcinoma (PDAC). Methods and results: Our study population consisted of 398 consecutive PDAC patients, who completed neoadjuvant therapy and PD between 1999 and 2012. Lymph node status was classified as ypN0 (node-negative), ypN1 (1-2 positive nodes) and ypN2 (≥3 positive nodes) and correlated with disease-free survival (DFS) and overall survival (OS). The ypN0, ypN1 and ypN2 was present in 183 (46.0%), 117 (29.4%) and 98 (24.6%) patients, respectively. Additionally, 162 (40.7%) had a lymph node ratio (LNR) ≤0.19 and 53 (13.3%) had a LNR >0.19. Patients with ypN1 disease had shorter DFS and OS than those with ypN0 disease, but better DFS and OS than those with ypN2 disease (P <0.05). Similarly, patients with a LNR ≤ 0.19 had better DFS and OS than those with a LNR > 0.19 (P <0.001). In multivariate analysis, both the number of positive nodes and LNR were independent prognostic factors for DFS and OS. Conclusions: Subclassification of post-therapy node-positive group into ypN1 (1-2 positive nodes) and ypN2 (≥3 positive nodes) should be incorporated into the American Joint Committee on Cancer (AJCC) staging of PDAC patients.