This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
The staging system for thymoma was developed by: 
Select and explain. 
A. Masaoka, B. Yokohama, C. Todani, D. Kluive
A: Masaoka
Answer: A: Masaoka 
Explanation: The staging system for thymoma was developed by Masaoka The stage is increased on the basis of the degree of invasiveness. The 5-year survival in stage I, 96%; stage II, 86%; stage III, 69%; stage IV, 50%. The French Study Group on Thymic Tumors (GETT) has modified the Masaoka scheme based on the degree of surgical removal. Ref: Harrison, E-18, chapter e-20.