Pattern of lymph node metastasis spread in pancreatic cancer

Objectives: We aimed to clarify the detailed pattern of lymph node (LN) metastasis spread in patients with pancreatic cancer. Methods: This retrospective study enrolled 429 patients who underwent pancreatectomy with extended lymphadenectomy for pancreatic cancer. The prognostic implications of LN metastasis were evaluated, and the position, frequency, and association with other clinicopathologic factors were investigated. Results: Lymph node metastasis was confirmed pathologically in 289 patients (67.4%). The prognosis of patients with LN metastasis was significantly poorer than that of patients without LN metastasis (P < 0.001). Distant LN metastasis occurred frequently, regardless of the tumor site. Patients classified with T1 or T2 only had regional LN metastasis, whereas there was a high rate of distant LN metastasis, including the para-aortic LNs, in patients with T3 or higher-stage tumors. Para-aortic LN metastasis was significantly associated with arterial and perineural invasion (P = 0.006 and P < 0.001, respectively). Lymph node metastasis in the hepatic portal region was a strong predictor of para-aortic LN metastasis in pancreatic head cancer. Conclusions: Pancreatic cancer frequently metastasized to distant LNs via a complex pathway and developed into systemic disease. Aggressive multimodality therapy, including neoadjuvant therapy, is essential to improve the long-term survival of patients at substantial risk of distant LN metastasis.