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: Surgery
The ideal timing of radiotherapy for Willm's tumor after surgery is - 
Select and explain. 
A. Within 10 days, B. Within 2 weeks, C. Within 2 months, D. Any time after surgery
A: Within 10 days
Answer: A: Within 10 days 
Explanation: The postoperative radiotherapy in Wilm's tumor is started within 10 days of surgery.
Delay in starting radiotherapy beyond ten days leads to tumor cells repopulation and increases the relapse rate.