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
[{'content': 'In Esophageal cancer prognosis is best determined by: \nSelect and explain. \nA. Cellular differentiation, B. Age of patient, C. T stage, D. Length of involvement', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Prognosis Long term survival following esophagectomy depends on - Depth of tumor invasion (T) - Number of involved lymph nodes (N) - Location of the tumor in the esophagus Prognosis is better for tumors of the cervical esophagus and at GE junction, in comparison to tumors located in the thoracic esophagus.', 'role': 'assistant'}]