Clinical characteristics of adenosquamous esophageal carcinoma

Primary adenosquamous carcinoma (ASC) of the esophagus is a rare entity. Most descriptions of this variant of esophageal cancer consist of case reports or small case series (1-13). While most reports from the western world are single cases, recently small case series have been reported from China and Japan (14-17). To the best of our knowledge, no case series have been reported from the United States. Therefore, little information exists regarding the demographics, clinical characteristics and outcomes associated with this disease. The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute collects data from various locations and sources throughout the United States. SEER currently collects cancer incidence and survival data from population based cancer registries that cover approximately 30% of the US population. This translates to available information on a large number of tumors of any single organ. Therefore, the SEER database serves as a useful resource to get a snapshot of the basic features of rare tumors that are unlikely to be treated in any single institution. Given the rarity of adenosquamous cancers of the esophagus and the availability of the SEER database, we sought to study the clinical characteristics of ASC in the United States. We also compared these characteristics to those of the commonly treated adenocarcinoma (ACA) and the increasingly uncommon squamous cell carcinoma (SqCC) of the esophagus