Prognostic impact of para-aortic lymph node status in resected pancreatic ductal adenocarcinoma and invasive intraductal papillary mucinous neoplasm - Time to consider a reclassification?

Background: Para-aortic lymph node (PALN) metastases in pancreatic ductal adenocarcinoma (PDAC) correlates with poor prognosis. The role of PALN in invasive intraductal papillary mucinous neoplasms (inv-IPMN) has not been well explored. The present study investigated the rate of metastatic PALN, lymph node ratio (LNR) and the overall nodal (N) status as prognostic factors in PDAC and inv-IPMN.

Methods: This consecutive single-center series included patients with PDAC or inv-IPMN in the pancreatic head who underwent pancreatoduodenectomy or total pancreatectomy, including PALN resection between 2009 and 2018. Median overall survival (mOS) and impact of clinicopathological factors, including PALN status on survival, were evaluated.

Results: 403 patients were included, 314 had PDAC and 89 inv-IPMN. PALN were metastatic in 16% of PDAC and 17% of inv-IPMN. N0 status was present in 6% of the patients with PDAC and 16% of inv-IPMN patients (p = 0.007). LNR >15% was more common in PDAC (52%) than in inv-IPMN (34%) (p = 0.004). mOS was 12.7 months in the presence of PALN metastases and 22.7 months without (p < 0.0001). Age >70 years, CA19-9 >200 U/mL, PDAC and N2 status were significantly associated with worse survival in a multivariable analysis. PALN status and LNR were not independent prognostic factors. In N2 status mOS was similar regardless the presence of PALN metastases.

Conclusion: The frequency of PALN metastases was similar in PDAC and inv-IPMN. Although PALN positive status entailed a shorter mOS, it was not an independent risk factor for death, and did not influence survival in N2-staged disease. The M1-status for PALN positivity may need reconsideration.