Impact of anatomic site of biliary tract tumour origin and conditional probability of survival (CS): Results from 15 prospective advanced first-line clinical trial

Background Inclusion of all patients (pts) with advanced biliary tract cancer (aBTC), irrespective of anatomic location, with assessment of overall survival (OS) in prospective trials, is debated. Additionally, outcome is typically described as estimated OS, but CS offers more relevant information once pts have survived for some time; this study assessed the impact of anatomic site of BTC origin and CS. Methods Pts enrolled into 15 prospective first-line aBTC clinical trials were included. OS was analysed using Cox proportional hazard regression; CS and 95% confidence intervals (CIs) were calculated. Results Overall, 1333 pts were included (Jan 97-Dec 13) with a median (med) age of 63 yrs (range 23-85); 46% male; 84% ECOG PS 0/1; 25% locally advanced (LA) stage, 72% metastatic (met), and 3% not reported (NR). Anatomic site of origin was gallbladder (GBC): 385 (29%), cholangiocarcinoma not specified (CCA-NS): 363 (27%), extrahepatic (EHC): 247 (19%), intrahepatic (IHC): 209 (16%), ampulla: 53 (4%) and 76 (6%) NR. Treatment was mono-chemotherapy: 310 (23%), cis/gem combination: 482 (36%), other combination: 520 (39%) and NR: 21 (2%). Med OS: 10.2 mths (95% CI 9.6-10.9). All sites, adjusted for treatment, had decreased risk of death vs GBC: EHC (p .05, p=.08 respectively). Conclusions Pts with GBC have worse OS compared to other anatomic BTC sites. Inclusion of other BTC subtypes, at least, in prospective aBTC clinical trials is justified. Conditional probabilities allow adjusted prognosis prediction for survivors with aBTC. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.