Comparison of clinical features by primary site in patients with biliary tract cancer who received gemcitabine-based chemotherapy: an exploratory analysis of JCOG1113.

Background: Biliary tract cancers (BTCs) are heterogenous malignancies including gallbladder cancer (GBC), intrahepatic cholangiocarcinoma (IHCC), extrahepatic cholangiocarcinoma (EHCC), and ampulla of Vater cancer (AVC). The reported data about the differences between the primary sites are limited to data that have just evaluated the efficacy of the treatment arms by primary site in randomized controlled trials. We aimed to compare the clinical features and treatment efficacy among the primary sites of BTCs using data from JCOG1113, a randomized trial.

Methods: Among the 354 patients enrolled in JCOG1113, 352 patients were included in this analysis. We compared the patient characteristics, and efficacy outcomes among the primary sites.

Results: There were more women (58.4%), and more patients with metastatic disease (78.1%) and multiple organs involving metastases (49.3%) in GBC compared to other primary sites. The median progression-free survival (PFS) was 5.7 months, 6.2 months, 8.7 months and 4.1 months for GBC, IHCC, EHCC and AVC, respectively. The median OS was 12.6 months, 15.7 months, 16.3 months and 11.5 months for GBC, IHCC, EHCC and AVC, respectively. Multivariable analysis revealed that GBC was identified as one of the prognostic factors for PFS compared with EHCC but was not significant for OS.

Conclusions: In this study, there were several findings regarding the differences in the clinical features, treatment efficacy, and prognosis among the primary sites. Patients with GBC were more likely to have metastatic disease and multiple metastases. GBC was an independent prognostic factor for PFS compared with EHCC, but was not for OS.

Clinical trial registration: JCOG1113 was registered with University hospital Medical Information Network Clinical Trials Regisry (UMIN000010667).