Do patients with metastatic pancreatic adenocarcinoma to the lung have improved survival?

Abstract

e16257 Background: Pancreatic ductal adenocarcinoma (PDAC) is a genetically heterogeneous disease often diagnosed with synchronous metastatic disease involving the liver. Tumors with extra-abdominal spread that bypass the liver are thought to represent a unique molecular subgroup of the disease. Specifically, those with isolated pulmonary metastatic disease are thought to have a more favorable clinical phenotype. We sought to retrospectively investigate whether patients with isolated pulmonary metastases had improved survival compared to those with disease involving the liver. Methods: We conducted a retrospective review of patients with pathologically confirmed PDAC treated between the years 2010 and 2020 at a Scripps Health hospital. The final study sample included only patients with pulmonary and/or liver primary metastases (N = 175). Analyses were conducted on subgroups defined by metastatic sites of disease in the liver only, lung only and combined liver+lung. Primary and secondary outcome analyses compared isolated lung versus liver/liver+lung. Primary endpoint was overall survival (OS), defined as from the date of diagnosis to date of death or most recent follow up. Progression free survival (PFS) was also analyzed as a secondary endpoint and defined as from the date of diagnosis to date of radiographic progression. Each survival outcome was analyzed using Cox Proportional Hazards tests. Results: No statistically significant differences were seen in OS (HR 0.67, CI 0.44–1.03; p= 0.069) or PFS (HR 1.05, CI 0.68–1.65; p= 0.816) between patients with primary lung metastases compared to those with either liver or liver+lung metastases (reported as hazard ratios of liver/liver+lung relative to lung only). However, a trend towards improved OS was seen for patients with isolated lung metastasis and the kaplan-meier curve for OS showed improved survival for these patients at 3 years, with crossing of the survival curves around 5 years from time of diagnosis. Conclusions: There appears to be a unique clinical phenotype in patients with PDAC presenting with isolated pulmonary disease. Though there was not a statistically significant difference in OS and PFS seen in our population, there was a trend towards improved overall survival compared to those with hepatic involvement. These findings highlight a potential prognostic indicator of metastatic PDAC and further subgroup analysis will help characterize clinical variations that may lead to these differences in tumor biology.[Table: see text]