This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oesophagus, Subject name: Surgery
Most common site for squamous cell carcinoma of esophagus is 
Select and explain. 
A. Upper 1/3, B. Middle 1/3, C. Lower 1/3, D. Upper 1/2
B: Middle 1/3
Answer: B: Middle 1/3 
Explanation: Ans. is 'b' i.e., Middle 1/3* Esophageal Carcinoma is of two common histological typesi) Squamous cell Ca - the MC type in world (-95% according to Sabiston)ii) Adenocarcinoma - where incidence is increasing at a rapid rate and is now the MC type in USA (Ref: Harrison, Schwartz)* Distribution of Squamous Cell Ca.# Upper 1/3 - 10%# Middle 1/3 - 60%# Lower 1/3 - 30% * Adenocarcinoma is mainly located in lower 1/3.