Real-world treatments and outcomes of resected biliary tract cancers in British Columbia, Canada.

505 Background: Complete resection followed by adjuvant chemotherapy is standard of care for patients with localized cholangiocarcinoma (CC) or gallbladder cancer (GBC) but is not always feasible and recurrence rates remain high. Understanding the exact proportions and reasons for treatment failure is important to design new approaches, data regarding this information remain scarce. Methods: We performed a retrospective population-based review of patients with GBC or CC (intrahepatic (ICC) or extrahepatic (ECC)) resected between 2005-2019 using the BC Cancer provincial database. Chart review was conducted to characterize demographics, treatments and outcomes. Results: 594 patients were identified of whom 416 (70%) had disease recurrence. Baseline characteristics and treatments received are shown in the table. Most GBCs (96%) were diagnosed incidentally. Repeat oncologic resection was performed for 55% of these, the most common reason for not proceeding was interval disease progression between initial cholecystectomy and planned re-resection (24%). Adjuvant chemotherapy was received by 51% of 163 patients after 2017 and consisted of capecitabine (86%), gemcitabine (4%), cisplatin and gemcitabine (5%) or chemoradiation (4%). Common reasons for not receiving adjuvant therapy were post op complications or comorbidities (18 and 24%), progression (17%) and patient’s preference (17%). Of those receiving adjuvant therapy, 31% did not complete all planned cycles due to progression (45%) or intolerance (55%). Median overall survival (OS) after resection was 31.6 and 18.0 months respectively for R0 and R1 resection (HR 0.43, 95% CI 0.35-0.53), 29.4 and 19.0 months with and without reresection for GBC (HR 0.55, 95% CI 0.41-0.73), and 29.4 and 25.9 months with and without adjuvant therapy (HR 0.79, 95% CI 0.61-1.02). Stage, R0 resection, re-resection for GBC and adjuvant chemotherapy remained associated with improved OS in multivariate analysis. Taken together, only 25% of patients in the more contemporary cohort of 2017-2019 had complete (R0) resection and completed adjuvant chemotherapy. Conclusions: Complete resection, including reresection for incidentally diagnosed GBCs, and adjuvant chemotherapy were associated with improved outcomes in this retrospective cohort, yet many patients were not able to complete these treatments. Neoadjuvant strategies may improve treatment delivery and ultimately, outcomes. [Table: see text]