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 important prognostic factor of cancer esophagus: 
Select and explain. 
A. Length of growth, B. Depth of involvement, C. Histology grading, D. Immunohistochemistry
B: Depth of involvement
Answer: B: Depth of involvement 
Explanation: Ans. (b) Depth of invasionRef: Bailey and Love 27th Edition, Page 1085 Prognostic factors of cancer esophagus:* Depth of invasion* Lymph node status* Presence of distant metastasis* Resection margin* Serosal or Peritoneal involvement* Vascular invasion