ADJUVANT CHEMORADIATION IN RESECTED BILIARY ADENOCARCINOMA: A VALIDATION OF SWOG S0809 USING A LARGE NATIONAL DATABASE
Dana Dominguez*, Yi-Jen Chen, Daneng Li, Gagandeep Singh, Yuman Fong, Laleh G. Melstrom
City of Hope, Duarte, CA
Introduction: There is a paucity of evidence supporting the use of adjuvant radiation therapy in resected biliary cancer. National guidelines recommend the consideration of use in patients with positive margins after resection, however, supporting evidence comes mainly from a phase II trial of 79 patients, SWOG S0809, which demonstrated that the use of adjuvant chemoradiation was well tolerated and resulted in an overall median survival of 35 months. We aimed to use a large national database to evaluate the use of adjuvant chemoradiation in resected extrahepatic bile duct and gallbladder cancer.
Methods: Using the National Cancer Database (NCDB), we selected patients from 2004-2017 with pT2-4, pN0-1, M0 extrahepatic bile duct or gallbladder adenocarcinoma with either R0 or R1 resection margins, and examined factors associated with overall survival using Cox proportional hazards model. We also examined overall survival in a subset of patients who received adjuvant chemo- and radiotherapy (CRT) using the Kaplan-Meier method and log rank test.
Results: Overall, 4,997 patients with gallbladder or extrahepatic adenocarcinoma with available survival information meeting the SWOG S0809 criteria were selected from the NCDB, 469 of whom received both adjuvant chemo- and radiotherapy. Of the CRT cohort, all patients received multi-agent chemotherapy, 211 (45.0%) had extrahepatic cholangiocarcinoma and 258 (55.0%) had gallbladder cancer, the majority were pT3 (n=281, 59.9%), pN1 (n=323, 68.9%), and had an R0 resection (n=387, 82.5%). Median overall survival in patients undergoing CRT was 36.9 months, and was not different between primary sites (p=0.841). Patients with a R1 margin had abbreviated overall survival compared to patients with an R0 resection (41.8 months vs 24.1 months, p<0.001). On multivariable cox regression analysis of all patients who underwent resection agnostic to adjuvant therapy, age, insurance status, Charlson-Deyo comorbidity index, T-stage, N-stage, lymphovascular invasion, margin status, chemo- and radiotherapy were all associated with overall survival. Adjuvant chemoradiation compared to chemotherapy alone showed an overall survival benefit for patients with either R0 (41.8 vs 30.8 months, p<0.001) or R1 (24.1 vs 20.2 months, p<0.001) resections.
Conclusion: Using a large national database, our data validates the findings of SWOG S0809 with a similar median overall survival in patients receiving chemoradiation. Patients receiving CRT had improved overall survival compared to patients receiving chemotherapy only after both R0 and R1 resections. These data further support the consideration of adjuvant multi-modal therapy in resected biliary cancers, regardless of margin status.
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