Comparative Features And Overall Survival In Adenosquamous Carcinoma, A Rare Tumor Of The Esophagus.

e15541 Background: Esophageal adenosquamous carcinoma (ASC) is a rare, mixed-histology tumor with aggressive clinical behavior. Having characteristics of both adenocarcinoma (AC) and squamous cell carcinoma (SCC), the two most common esophageal cancers, its behavior is poorly understood, with the current literature limited to case studies and small case series. Using the National Cancer Database (NCDB), an outcomes directory representing approximately 70% of new cancer diagnoses in the United States, we compared the largest number of known cases of esophageal ASC to AC and SCC in terms of patient demographics, clinicopathologic features, and overall survival. Methods: The NCDB was queried for patients diagnosed with esophageal ASC, AC, and SCC between 1998 and 2011. Univariate association with histologic group was analyzed using the χ2 test and ANOVA, where appropriate. Univariate association with overall survival was analyzed using Cox proportional hazard model and log-rank tests. Kaplan-Meier plots were used to compare survival by histologic group. Propensity score weighting was applied to balance demographic and socioeconomic characteristics among patients. Results: Between 1998 and 2011, 897 patients in the NCDB were identified as having esophageal ASC, 69,877 as having esophageal AC, and 34,312 as having esophageal SCC. The patients were commonly male (79.5% of ASC, 85.3% of AC, and 64.5% of SCC) and Caucasian (89.2% of ASC, 95.2% of AC, and 65.5% of SCC). The median age at diagnosis was 65 for both ASC and AC and 67 for SCC. The median size of tumor was 4.5 cm for both ASC and SCC and 4.0 cm for AC. Clinical N stage was > 1 in 58.3% of ASC, 54.6% of AC, and 53.7% of SCC. Clinical m stage was 0 in 69% of ASC, 70.9% of AC, and 75.6% of SCC. Median survival was 9.6 months in ASC, 9.7 months in SCC, and 13.5 months in AC. Two-year overall survival was 23.8% in ASC, 26.5% in SCC, and 34.6% in AC. All p < 0.001. By propensity score weighting, the overall survival hazard ratio for ASC was 1.1 when compared to SCC (95% CI = 1.18-1.01, p = 0.02), and 1.23 when compared to AC (95% CI = 1.33-1.15, p < 0.001). Conclusions: ASC is a rare tumor subtype among esophageal carcinomas with aggressive clinical behavior and a prognosis worse than either AC or SCC.