Systemic Treatment Alone Versus Systemic Treatment Plus Radiotherapy in Oligometastatic Renal Cell Carcinoma

Inclusion Criteria: 1. Patients with metastatic renal cell carcinoma classified within the ESTRO/EORTC classification system as having ≤ 5 metastases, ≤ 3 metastatic organs, and meeting criteria for new, recurrent, or induced metastases. 2. Patients aged 20 to 80 years. 3. Patients with individual metastases ≤ 5 cm in longest diameter. 4. Patients with primary tumors surgically removed or scheduled for surgery. 5. Patients histologically diagnosed with clear cell carcinoma. 6. Patients with ECOG performance status 0-1. 7. Patients with normal major organ function and bone marrow function meeting specific criteria: WBC ≥ 2,000/μL, neutrophils ≥ 1,000/μL, platelets ≥ 50,000/μL. 8. Patients who understand the contents of the informed consent form, voluntarily consent to participate in the study, and sign the informed consent form. 9. Patients who agree to use contraception from the time of signing the consent form until 1 year after the last standard systemic therapy. 10. Breastfeeding women who agree to stop breastfeeding for at least 5 months after the last standard systemic therapy. 11. Patients with visible tumors outside the scope of tumor removal surgery (surgical therapy) for metastatic lesions. Exclusion Criteria: 1. Patients with total bilirubin \> 3.6 mg/dL. 2. Patients with AST \>160 U/L, ALT \> 165 U/L. 3. Patients unable to maintain position for partial nephrectomy radiotherapy. 4. Patients with a history of radiotherapy to metastatic renal cell carcinoma or surrounding areas. 5. Patients with confirmed brain, peritoneal, or pleural metastases. 6. Patients diagnosed with another solid tumor and treated within 2 years or with residual lesions. 7. Patients who do not consent to participate in the study. 8. Pregnant patients.