Background: Patients with liver-only metastatic pancreatic adenocarcinoma have traditionally been offered palliative chemotherapy alone. Recent studies have explored the role of surgical resection among patients with limited metastatic disease. National practice patterns and the impact of surgery among these patients remains unknown.
Methods: The National Cancer Database was queried for all patients with pancreatic adenocarcinoma between 2010 and 2015. The primary outcome was overall survival from the time of diagnosis. Patients with liver-only metastatic disease were included. Univariable and multivariable logistic regression models were constructed to determine the association of patient, hospital, and regional factors with receipt of surgical resection. A propensity score-matched cohort (1:1) was generated by matching patient- and tumor-related factors (age, sex, race, comorbidity burden, primary tumor site, primary tumor size) among patients with liver-only stage IV pancreatic adenocarcinoma who received chemotherapy alone compared to those who received chemotherapy and underwent pancreatectomy and liver metastatectomy.
Results: Among 312,426 patients who met the study criteria, one half (n = 140,043, 50.4%) had stage IV disease; metastatic sites included bone (n = 5493, 3.1%), brain (n = 620, 0.4%), lung (n = 16,580, 9.5%), and liver (n = 62,444, 35.7%). Patients with stage IV disease were more likely to be younger (odds ratio: 1.10, 95% confidence interval: 1.0-1.2; P = .03) and have poorly (odds ratio: 2.1, 95% confidence interval: 1.8-2.5; P < .001) or undifferentiated (odds ratio: 3.1, 95% confidence interval: 2.3-4.1; P < .001) tumors. Among stage IV patients with liver-only disease (n = 47,785, 14.9%), 891 patients (1.9%) underwent pancreatic resection. Patients who underwent resection were more likely to be younger (odds ratio 1.4, 95% confidence interval: 1.0-1.8; P = .03) and treated at an academic/research center (odds ratio 2.1, 95% confidence interval: 1.2-3.5; P = .006). Median overall survival among patients who underwent resection was 10.74 months versus 3.4 months among patients who did not undergo resection. After controlling for patient and disease-related factors, patients who underwent surgical resection had a lower risk of death versus patients who did not undergo surgery (hazard ratio: 0.5, 95% confidence interval: 0.4-0.6; P < .001). After propensity score matching, patients who received multimodality treatment for liver-only metastatic pancreatic adenocarcinoma (surgery, chemotherapy) had a longer median overall survival (15.6 months vs 8.1 months) compared to those who received chemotherapy alone (P < .001).
Conclusion: This study suggests that pancreatic resection in patients with liver metastases, in combination with chemotherapy and/or chemoradiation, may be associated with improved survival in well-selected patients. However, attempts at an aggressive surgical approach for patients with liver-only stage IV pancreatic adenocarcinoma patients should only be performed only under a well-designed prospective clinical trial.
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