This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Esophagus, Subject name: Surgery
Squamous cell carcinomas of the esophagus most commonly occur 
Select and explain. 
A. At the GEJ, B. Middle 1/3rd, C. In the lower thoracic esophagus, D. Evenly distributed throughout the esophagus
B: Middle 1/3rd
Answer: B: Middle 1/3rd 
Explanation: - MC type of CA Esophagus World Wide - Squamous cell carcinoma- MC type of CA in western countries - Adenocarcinoma- MC site of Squamous cell carcinoma - Middle 1/3rd- MC site of Adenocarcinoma - Lower 1/3rd- MC site of CA Esophagus overall - Middle 1/3rd- SCC - more common in low socio-economic status- Adenocarcinoma - more common in high socio-economic status