Clinical characteristics of adenosquamous esophageal carcinoma

Background: Current published information of adenosquamous carcinoma (ASC) of the esophagus in the United States is limited to isolated case reports. We sought to study the clinical characteristics of this tumor using the Surveillance, Epidemiology and End Results (SEER) database. Methods: Relevant data of all patients with esophageal cancer in the SEER database diagnosed from 1998-2010 was obtained. Demographic, grade, stage, treatment and survival characteristics of patients with ASC were summarized and compared to those patients with adenocarcinoma (ACA) and squamous cell carcinoma (SqCC). Univariate analyses across comparison groups were performed using Wilcoxon rank sum test for continuous covariates and the Pearson Chi-square test for categorical covariates. To evaluate the association of selected covariates to survival by histology, unadjusted and adjusted proportional hazards models were generated for the entire study population. To further control for the difference in covariates among the histology groups, propensity weighted Cox regression modeling was performed using the inverse propensity to treat weighting (IPTW) approach. Results: Of 29,890 patients with the histological subgroups, only 284 patients had ASC (1%). Patients with ACA had a higher grade (72.9% with grade III/IV) and presented with advanced stage (48.2% distant disease) than their comparison group. Patients with ASC had worse overall survival compared to ACA but not SqCC in both univariate and multivariate analyses (OR = 0.76; P<0.05 and OR = 0.86; P<0.05 respectively). These results were further confirmed by the propensity weighted Cox regression analysis. Analysis of the ASC population alone demonstrated that decreasing stage, radiation therapy (OR = 0.59; P<0.001) and surgery (OR = 0.86; P<0.001) were associated with better overall survival, but grade was not. Conclusions: ASC of the esophagus is a rare histological variant comprising 1% of esophageal ACA in the Unites States. This histological subtype presents in later stages, at a higher grade and portends a poorer survival than the more common ACA. Radiation therapy and surgical resection of appropriate stage patients provide the best chance of survival.