J. M. Levine1, I. F. Rompen1,2, J. Campos Franco1, B. Swett1, M. Kryschi2, N. Mughal1, J. R. Habib1, B. Hewitt1, S. M. Cohen1, C. L. Wolfgang1, A. A. Javed1,3 1The NYU Grossman School of Medicine and NYU Langone Health, Department Of Surgery, New York, NY, USA 2Heidelberg University Hospital, Department Of General, Visceral, And Transplantation Surgery, Heidelberg, BADEN-WÜRTTEMBERG, Germany 3Amsterdam UMC, University of Amsterdam, Cancer Center, Department Of Surgery, Amsterdam, NORTH HOLLAND, Netherlands
Introduction:
Approximately half of all patients with pancreatic ductal adenocarcinoma (PDAC) present with metastatic disease, and life expectancy is less than one year. However, recent retrospective studies demonstrate a survival benefit associated with aggressive treatment, including surgery, for oligometastatic PDAC. The site of metastasis plays a crucial role in clinical decision-making due to its prognostic value. However, no study has assessed the longitudinal impact of metastatic site on outcomes. The aim of this study was to determine the role of site-specific metastatic patterns over time and assess factors associated with longer survival in metastatic PDAC.
Methods:
We searched the National Cancer Database (NCDB) for all patients diagnosed with stage IV PDAC between 2016 and 2019. Patients were classified by site of metastatic disease at diagnosis: multiple, liver, lung, brain, bone, carcinomatosis, or other. Furthermore, demographic, clinical, and pathological characteristics were compared between long-term survivors (>3 years) and short-term survivors. To assess the prognostic value of metastatic sites, we used Kaplan-Meier analysis and log-rank for survival testing at different time points.
Results:
A total of 56,757 patients with metastatic stage IV PDAC were identified. Most patients presented with liver metastases (51.5%) followed by multiple sites (31.2%), “other” (9.4%), lung (4.9%), distant lymph node (1.6%), bone (0.9%), carcinomatosis (0.6%), and brain (0.1%). At diagnosis patients with distant lymph node metastases (9.0 months) and lung metastases (8.1 months) had better survival compared to patients with liver-only metastases (4.6 months, P<.001). However, after six months, the metastatic site lost its prognostic value.
In patients who survived beyond three years (N=2052, 3.6%), those with liver disease (69.1 months, P<.001) had a longer survival compared to those with lung disease (56.8 months). On univariate analysis, long-term survivors were more likely to be younger, female, Hispanic, privately insured, higher income earners, have a Charlson index <2, have received chemotherapy, or have had a surgery of their primary tumor.
Conclusion:
This study demonstrates that while at diagnosis liver metastases predicts worse outcomes for patients with metastatic PDAC as compared to lung and lymph node metastases, this predictive value is lost once patients make it to six months of survival. Therefore, beyond this window, treatment decisions should not primarily be based on the site of metastatic disease. Long-term survival may be achieved in a small subset of patients; however, treatment disparities must be further explored in order to make treatment accessible to all eligible patients.
