Real-world outcomes in recurrent versus de novo metastatic pancreatic adenocarcinoma.

Abstract

387 Background: Optimal management of patients with recurrent pancreatic ductal adenocarcinoma (PDAC) is unknown. In the clinical trials that established a survival benefit with combination chemotherapy compared to single agent gemcitabine, patients with recurrent PDAC were either excluded (PRODIGE-4) or severely underrepresented (MPACT). In this study, we evaluated clinical outcomes of recurrent PDAC patients who receive systemic therapy and compared outcomes to patients with de novo advanced PDAC. Methods: Patients diagnosed with advanced PDAC between 2014 and October of 2019 were included using the nationwide Flatiron Health EHR-derived de-identified database. Patients without a clinic visit or initiation of treatment within 90 days of diagnosis were excluded. Patients were characterized as either de novo or recurrent PDAC based on stage at diagnosis and history of surgery. Patients with recurrent PDAC were further stratified based on time to recurrent disease. Overall survival (OS) was summarized within groups via Kaplan-Meier survival estimates, and compared between groups in the context of univariable and multivariable Cox proportional hazards models. The covariates adjusted for were gender, age, race, ECOG, smoking status, primary site, CA199, albumin, lymphocytes, neutrophils and monocytes. Results: We included 5170 patients with advanced PDAC, of which 1101 (21.3%) met criteria for recurrent disease. Patients with recurrent PDAC were more likely to have tumors in the head of the pancreas (71% vs 40%, p < 0.001) and had lower median CA19-9 (92.8 vs 617, p < 0.001), compared to the de novo PDAC patients. Median OS for the recurrent group was 10.8 m (95% CI = 9.9-11.7) vs. 7.3 m (95% CI = 7.0-7.7) in the de novo group (p < 0.001, both univariate and multivariable adjusted analyses). The most common first line palliative chemotherapy in patients with recurrent disease was Nab-paclitaxel plus gemcitabine (41%) or FOLFIRINOX (21%). Patients who recurred within six months of surgery (28%) had an OS of 10.0 m (95% CI = 8.7 -11) vs. 11.6 m (95% CI 10-12, p = 0.256) in those who recurred greater than six months from surgery. Conclusions: Our data suggest that patients with recurrent disease have significantly better survival outcomes compared to patients with de novo metastatic disease. We did not observe a significant difference in survival of patients who recurred within 6 months of resection compared to those who recurred greater than six months after surgery. These data support the inclusion of patients with recurrent PDAC in clinical trials, including those who develop recurrent disease within 6 months of surgery, with appropriate stratification for these variables.