This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Esophageal Diseases - Gastroesophageal Reflux Disease, Carcinoma, Subject name: Surgery
Barrets esophagus is commonly associated with one of the following: 
Select and explain. 
A. Adenocarcinoma, B. Squamous cell carcinoma, C. Sarcoma, D. Gastrointenstinal stromal tumor
A: Adenocarcinoma
Answer: A: Adenocarcinoma 
Explanation: Ans. is 'a' i.e. Adenocarcinoma Barret's esophagus is the single most important risk factor for adenocarcinoma of esophagus.Barret's esophagus is metaplastic change of distal esophageal mucosa from normal squamous epithelium to columnar epithelium, in response to chronic gastro-esophageal reflux.The junction between squamous esophageal mucosa and gastric mucosa moves proximally.The risk of adenocarcinoma increases with increasing length of columnar-lined epithelium.The adenocarcinoma develops at the squamo-columnar junction (85%) or within 2 cm of the junction.Other complications of Barett's esophagus include : peptic ulcers in the columnar lined seg. of esopahgushigh and long strictures occur at the squamo-columnar junction and move high up as the squamo- columnar junction moves up with progressive injury.