Unexpected Para-aortic Lymph Node Metastasis in Pancreatic Ductal Adenocarcinoma: a Contraindication to Resection?

Abstract

Background Margin-negative resection is the only cure for pancreatic cancer. However, para-aortic lymph node metastasis is considered a contraindication to curative resection in pancreatic cancer. To determine if there are long-term survival differences according to the presence or absence of para-aortic lymph node metastasis in patients undergoing pancreatectomy, we evaluated oncologic outcomes in resected pancreatic cancer with unexpected para-aortic lymph node metastasis confirmed on intraoperative frozen section biopsy. Methods We retrospectively investigated 362 patients with pathologically confirmed pancreatic ductal adenocarcinoma who underwent pancreatectomy between 1996 and 2016. Results Patients with a metastatic para-aortic lymph node had the poorest median disease-specific survival [hazard ratio 14, 95% confidence interval 10-19]. However, after chemotherapy, patients with a metastatic para-aortic lymph node had a much higher disease-specific survival rate (para-aortic lymph node+/postoperative chemotherapy- versus para-aortic lymph node+/postoperative chemotherapy+, P = 0.0003, adjusted P = 0.0015). Patients with a metastatic para-aortic lymph node who underwent postoperative chemotherapy had a similar survival benefit to patients with metastatic regional lymph node without para-aortic lymph node metastasis, regardless of postoperative chemotherapy (para-aortic lymph node+/postoperative chemotherapy+ versus regional lymph node+/postoperative chemotherapy-, P = 0.3047, adjusted P > 0.9999; para-aortic lymph node+/postoperative chemotherapy+ versus regional lymph node+/postoperative chemotherapy+, P = 0.0905, adjusted P = 0.4525). Conclusions Unexpected para-aortic lymph node metastasis on frozen section biopsy may no longer be a contraindication to curative resection in "resectable" pancreatic ductal adenocarcinoma, as long as postoperative adjuvant chemotherapy can be administered.