K. M. Turner1, C. J. Joyce1, A. R. Dhanarajan1, J. L. Gnerlich2 1Loyola University Chicago Stritch School Of Medicine,Maywood, IL, USA 2Louisiana State University Health Sciences Center,Surgery,New Orleans, LA, USA
Introduction: Over half of the patients diagnosed with pancreatic cancer have metastatic disease at presentation. Pancreatic resection is not considered an option for management of Stage IV pancreatic cancer; however, small institutional studies have shown a questionable survival benefit in select metastatic patients who underwent a pancreatectomy. For patients with low-volume metastatic disease and a good response to systemic therapy, questions regarding further management including surgery need to be addressed. Our aim is to determine if there is a survival advantage with surgical resection of the primary tumor in a large subset of patients with metastatic disease.
Methods: We conducted a retrospective, population-based cohort study of Stage IV pancreatic adenocarcinoma patients using the 2004-2013 Surveillance, Epidemiology, and End Results (SEER) database to compare patients who underwent surgical resection with patients who did not. Associations between patient characteristics and surgery were assessed for statistical significance with chi-square tests. Median survival time was calculated using the Kaplan-Meier method. Univariable and multivariable Cox proportional hazards models were used to determine the hazard ratios for patient and treatment characteristics associated with mortality.
Results: Of the 35,767 SEER patients with Stage IV pancreatic adenocarcinoma, 814 (2.3%) underwent pancreatic surgery and 34,953 (97.7%) did not receive surgery. Over the study time period, rates of pancreatic resection were similar. Overall, 6.0% of patients received radiation, 13.0% surgery group vs. 5.8% no surgery group (p<0.001). Patients who were younger, married, had lower grade, smaller tumors (<4cm), pancreatic head tumors, and those who received radiation were significantly more likely to undergo surgery (p<0.05 for each). On univariable Cox proportional hazards modeling, both radiation (HR: 0.68, 95% CI: 0.65-0.71) and surgery (HR: 0.47, 95% CI: 0.44-0.51) conferred a survival advantage. Median survival was longer for those who underwent surgery compared with those who did not undergo surgery (9 vs. 3 months, p<0.001). After adjustment for age, gender, race, tumor size, location, and radiation, surgery was associated with improved survival (aHR: 0.51, 95% CI: 0.47-0.56). Results were similar and remained significant in a sensitivity analysis considering cause-specific mortality.
Conclusion: Analysis of the 2004-2013 SEER data suggests that a subset of patients with Stage IV pancreatic cancer are undergoing surgery with improved survival. With increased survival times and response rates to multi-agent systemic therapy, future studies are needed to determine which metastatic patients will benefit from surgical resection.
