Comparative Outcomes of Adenosquamous Carcinoma of the Gallbladder: an Analysis of the National Cancer Database

Background: A paucity of data exists regarding adenosquamous carcinoma of the gallbladder, a histology comprising under 10% of gallbladder cancer diagnoses. The aim of this study is to characterize the clinicopathological features of these tumors utilizing a population-based dataset compared with gallbladder adenocarcinoma. Methods: We identified patients with gallbladder adenosquamous and adenocarcinoma from the National Cancer Database from 2004 to 2015. Patient demographics, tumor characteristics, treatment regimens, and overall survival were analyzed between the groups. Results: We identified 13,158 patients: 12,455 (95%) with a diagnosis of gallbladder adenocarcinoma and 703 (5%) with adenosquamous carcinoma. Adenosquamous tumors were larger, poorly differentiated, and presented with Stage III/IV disease (75% vs 69%, p < 0.001). Overall 1-, 3-, and 5-year survival for adenosquamous and adenocarcinoma were 24%, 11%, and 9% vs 37%, 16%, and 11%, respectively (p < 0.001). Following surgical resection, adenosquamous carcinoma had more positive margins (31% vs 25%, p < 0.001), and median overall survival was 10.3 months vs 20.5 months for adenocarcinoma (p < 0.001). Overall survival at 1-, 3-, and 5-years for surgically resected adenosquamous and adenocarcinoma were 43%, 23%, and 18% versus 63%, 35%, and 25%, respectively (p < 0.001). In resected adenosquamous carcinoma, positive lymph nodes and margins were associated with worse survival, while adjuvant chemoradiation (HR 0.457, 95% CI 0.31–0.69, p < 0.001) was associated with improved survival. Conclusion: Adenosquamous gallbladder cancer presented with larger tumors at advanced clinical stages when compared with adenocarcinoma. Overall survival was worse for adenosquamous tumors both overall, and following curative intent resection. Adjuvant chemoradiation was associated with improved survival in adenosquamous tumors.