This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Not a predisposing factor for Ca esophagus 
Select and explain. 
A. Diveicula, B. Human papilloma virus, C. Mediastinal fibrosis, D. Caustic ingestion
C: Mediastinal fibrosis
Answer: C: Mediastinal fibrosis 
Explanation: OESOPHAGEAL CARCINOMA,6 th most common carcinoma in the world, can be predisposed to dietary deficiencies, human papillomavirus infections, achalasia cardia, oesophageal webs etc.it is most commonly seen in middle third of oesophagus (50%)and also at lower third(33%) and upper third(17%).in the lower pa adenocarcinoma is common .in India 90%are squamous carcinomas.dysphagia, regurgitation, anorexia, loss of weight, ascites, palpable left supraclavicular lymph nodes are the clinical features. Ref: SRB&;s manual of surgery,5th ed, pg no805