This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genitourinary radiology, 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: Radiotherapy is to be staed within 10 days. Delay in staing radiotherapy for Wilms tumour can result in an increase in relapse rate