735P - Second-line chemotherapy (SLC) in patients with advanced biliary tract and gallbladder cancers (ABGC) prolongs survival: A retrospective population-based cohort study

Abstract

BackgroundLimited evidence is available regarding survival benefit of SLC in patients with ABGC. After failure of first-line treatment, currently no "standard" second-line therapy is available. There is a lack of randomized clinical trials and well-designed population-based study to address this important question in the management of ABGC. In this population-based cohort study we evaluated if SLC prolongs survival in patients with ABGC. MethodsPatients with biopsy proven ABGC who were diagnosed in the province of Saskatchewan during the period of 2006 to 2015 and received first-line chemotherapy were assessed. Based on the use of SLC, patients were divided into ‘Treatment’ group or ‘Control’. Cox proportional multivariate analyses were performed to determine survival benefit of SLC. Results136 eligible patients with median age of 66 (IQR, 55-73) and M:F of 1:1.34 were identified. Primary tumor sites were as followed: gallbladder 31%, intrahepatic cholangiocarcinoma 36%, bile duct 23%, and ampullary 10%. 68% patients had metastatic disease.37% patients received SLC and of those 42% received combination therapy. There were significant differences between the two groups with respect to age and baseline liver function. The median overall survival (mOS) of treatment group was 17 months (95%CI, 12.5-21.5) vs. 7 months (5.3-8.7) of control (p<0.0001). Patients who received combination SLC had mOS of 20 months (14.0-26.1) vs. 17 (13.5-20.5) with single agent chemotherapy (p=0.73). On progression 36% received 3rd or subsequent line treatment. On univariate analysis SLC HR 0.51 (0.35-0.73), bilirubin 0.52 (0.34-0.79), and neutrophil to lymphocyte ratio (NLR) 1.11 (1.07-1.16) significantly correlated with survival. Test for interaction between SLC and all the other variables were not significant. On multivariate analysis SLC HR 0.55 (0.36-0.83) and NLR 1.10 (1.05-1.15) were significantly correlated with survival. ConclusionsThis well-designed population based cohort study suggests a substantial survival benefit associated with SLC. Patients with ABGC who are potential candidate for chemotherapy should be offered active treatment or participation in the clinical trial. Legal entity responsible for the studyThe authors. FundingSaskatchewan Cancer Agency Research Grant. DisclosureAll authors have declared no conflicts of interest.