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: Radiology
The ideal timing of radiotherapy for Wilms tumour after surgery is – 
Select and explain. 
A. Within 10 days, B. Within 2 weeks, C. Within 3 weeks, D. Any time after surgery
A: Within 10 days
Answer: A: Within 10 days 
Explanation: The postoperative radiotherapy in Willm's tumor is started within 10 days of surgery. Delay in starting RT beyond 10 days leads to tumor cell repopulation and increase in relapse rate.