Clinicopathological features and survival outcomes of rare histologic variants of gallbladder cancer

Background Adenocarcinoma (AC) is the most common histological type in gallbladder carcinoma (GBC). Squamous cell carcinoma (SCC), adenosquamous carcinoma (ASC), and papillary carcinoma (PC) are rare histologic variants of GBC. Methods Patients with AC, SCC, ASC, and PC of the gallbladder between 2004 and 2013 were identified from the National Cancer Database. Univariate and multivariate analyses were performed, and Kaplan-Meier curves were used to compare overall survival (OS) based on histological subtype. Results A total of 5956 patients >= 18 years of age were included in the final analysis. Most patients (n = 5398; 90.6%) had AC compared with variant histologies. PC (n = 227; 3.8%) was the most common variant, followed by ASC (n = 216; 3.6%) and SCC (n = 115; 1.9%); 70.3% were female and 78.9% Caucasian. The median age was 70 (range, 25-90) years. Surgical resection was performed in 77.7% of AC, 53.0% of SCC, 88.9% of ASC, and 96.9% of PC (P < .001). Systemic therapy after surgery was administered in 25.1% of AC, 18.3% of SCC, 35.7% of ASC, and 19.4% of PC (P = .001). In multivariate analysis, multiagent chemotherapy was associated with improved OS in all histologies except for SCC and PC (p < .001), and adjuvant systemic therapy was associated with improved OS in ASC and AC (P < .001). Conclusion Survival differs between the gallbladder variants. Except for SCC, GBC variants underwent surgical resection more often than AC. Adjuvant systemic therapy was associated with improved OS in ASC and AC.