Impact of site of metastases in pancreatic ductal adenocarcinoma.

Abstract

708 Background: Metastatic pancreatic ductal adenocarcinoma (mPDAC) has a 5-year survival rate of 3%. We examined the clinical significance of the metastatic site on outcomes in mPDAC using the Surveillance, Epidemiology, and End Results (SEER) database. Methods: We analyzed the data on mPDAC from SEER database from 2010-2020 and categorized into three groups: mPDAC with, liver-only (LO) metastasis (mets), multi-organ mets including the liver (IL), and multi-organ mets excluding the liver (EL). Patient demographics and disease characteristics were summarized using the mean for continuous variables and proportions for categorical variables. Overall survival (OS) was calculated from time of diagnosis to death or censored at a loss to follow-up. The survival curve was plotted using the Kaplan-Meier method and log-rank p-value was reported. The Cox regression model was used to study the association of site of distant metastasis on overall survival, controlling for potential confounders (age, race, treatment, etc.) Results: We identified 22642 patients with mPDAC; 15844, 4250, and 2548 with LO, IL, EL mets respectively. The mean age at diagnosis was 66 years with the majority being white (78.4%), non-Hispanic (87.1%), and from metropolitan counties (88.5%). The median OS was 4 months, 3 months, and 6 months (log-rank p<0.001) for LO, IL, and EL groups respectively, with 2-year survival being 4.84%, 2.56% and 7.89% respectively (log-rank p<0.001). Multivariate analysis showed a higher risk of mortality in LO (31.5%, hazards ratio (HR)=1.315, p<0.001) and IL groups (69.2% HR=1.692, p<0.001) than EL group (Table). Conclusions: The site of distant metastasis is an independent prognostic factor for survival in patients with mPDAC, with liver-only mets or multi-organ mets including liver having worse OS than extrahepatic mets. [Table: see text]