Total Neoadjuvant Treatment for Pancreatic Ductal Adenocarcinoma Is Associated With Limited Lymph Node Yield but Improved Ratio.

INTRODUCTION

The lymph node yield (LNY) and lymph node ratio (LNR) of nodal metastases following pancreatoduodenectomy (PD) have been reported as prognostic parameters in patients with pancreatic ductal adenocarcinoma (PDAC). However, they have not been compared in the setting of various neoadjuvant therapy modalities.

METHODS

A single institutional retrospective study identified 134 patients diagnosed with resectable, BLR- and LA-PDAC who underwent PD at Fox Chase Cancer Center between 2010 and 2019. Patients were categorized based on first-line treatment as follows: surgery first (SF), total neoadjuvant therapy (TNT), and single modality neoadjuvant therapy (SMNT). The histopathological reports of the surgical specimens were examined to obtain LNY and determine the counts of lymph nodes with metastases. Subsequently, LNR was calculated as the number of positive lymph nodes divided by the number of lymph nodes examined.

RESULTS

Overall, 49, 38, 27, 12, and 8 patients underwent SF approach, SMNT, incomplete TNT, induction TNT, and consolidation TNT, respectively. There was no difference in R0 resection and vascular resection between the groups (P = 0.096 and 0.794, respectively). The median counts of LNY were 22, 15, 21, 11.5, and 10, respectively (P < 0.001). The average LNR was 0.16, 0.07, 0.03, 0.02, and 0.02, respectively (P < 0.001). There were statistically significant differences in overall survival in the TNT groups (log-rank test P = 0.030).

CONCLUSIONS

PDAC patients who undergo the TNT modality exhibit lower LNY and improved LNR compared with the SF approach and SMNT neoadjuvant therapy groups. This is likely explained by the increased treatment response and lymph node obliteration associated with the TNT approach. Our results question the minimal requirement of 11-18 harvested lymph nodes for PD following TNT.