**Study Using Risk Factors to Determine Treatment for Children With Favorable Histology Wilms Tumors** This study focuses on children with a type of kidney cancer called Wilms Tumor, especially the most common form, Favorable Histology Wilms Tumor (FHWT). Researchers are examining various risk factors to find better ways to treat this cancer and improve survival rates. Risk factors are things that can increase the chance of cancer returning after treatment. **Key Points:** - The study involves different treatment arms, including various chemotherapy regimens and observation. Treatment can last up to 14 cycles, with each cycle being about 21 days. - Participation requires multiple visits for treatments and follow-up care, including imaging tests like CT or MRI scans. - Eligibility includes children under 30 years with newly diagnosed Stage I-IV FHWT. Participants must be enrolled in a related screening study and meet specific health criteria. This research aims to tailor treatments based on individual risk factors, potentially reducing the intensity of therapy for some while ensuring others receive necessary treatments to prevent cancer relapse. Participants will be followed for 10 years to monitor outcomes.