Lymph node ratio is a reliable prognostic marker after neoadjuvant therapy and pancreaticoduodenectomy for pancreatic cancer, but does not predict the utility of adjuvant therapy

Abstract

Presenter: Alexandra Adams MD, MPH | Brooke Army Medical Center Background: Neoadjuvant chemotherapy (NAT) has been increasingly utilized for patients with pancreatic ductal adenocarcinoma (PDAC). However, the role of additional adjuvant chemotherapy (AT) after NAT and surgical resection remains unclear. The lymph node ratio (LNR), defined as the number of positive nodes divided by total resected nodes, is a well-established prognostic indicator for patients with resected PDAC, and could potentially help decipher which patients could avoid AT after NAT. The objective of this analysis was to determine if LNR predicts survival benefit from receipt of AT following NAT and surgical resection. Methods: Patients who underwent pancreaticoduodenectomy after NAT from 2006-2017 and had pathologically node positive PDAC were identified using the National Cancer Database. Patients with metastatic disease or unknown lymph node status were excluded. Patients were grouped as receiving NAT plus AT, or NAT only. The LNR within the node-positive groups were compared, with a cutoff of 0.15. Five-year overall survival was determined by Kaplan-Meier analysis and multivariate (MV) Cox proportional hazards modeling. Results: A total of 1,182 patients were included: 623 patients with LNR=0.01-0.14 and 559 with LNR>=0.15. Median survival was higher among patients with LNR=0.01-0.14 than those with LNR>=0.15 (28.8 vs 20.5 months, log-rank p=0.15, receipt of additional AT was associated with improved median survival of 23.3 months vs 18.2 months without AT (log-rank p=0.0024). MV analysis by Cox proportional hazards revealed similar survival benefit from AT, with hazard ratios of 0.807 (95% CI 0.678-0.960, p=0.0156) for LNR=0.01-0.14 and 0.794 (95% CI 0.669-0.942, p=0.0084) for LNR>=0.15. Conclusion: Although LNR is a reliable prognostic indicator for PDAC, it does not predict the utility of AT after receipt of NAT. Thus, while LNR may be useful in counseling patients regarding prognosis, we advise against using it as a discriminator for decisions regarding adjuvant therapy. Further investigation is needed into the best selection criteria for patients that would benefit from additional AT after receipt of NAT and pancreaticoduodenectomy.