This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, 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. Gastrointestinal stromal tumor
A: Adenocarcinoma
Answer: A: Adenocarcinoma 
Explanation: Barrett's oesophagus is a metaplastic change in the lining mucosa of the oesophagus in response to chronic gastro-oesophageal reflux . Squamous epithelium of lower end of the oesophagus is replaced by diseased columnar epithelium. When intestinal metaplasia occurs, there is an increased risk of adenocarcinoma of the oesophagus, which is about 25 times that of the general population.Reference : page 1022-23 Bailey and Love's sho practice of surgery 25th edition