Systemic Therapy Alone or With Stereotactic Body Radiotherapy for Oligometastatic Kidney Cancer (STROKER Study)

Inclusion Criteria: * Pathologically confirmed diagnosis of renal cell carcinoma of any histology * Age ≥ 18 years. * ECOG performance status of 0-2. * Imaging suggests the presence of distant metastases, with no more than 5 metastatic lesions according to RECIST 1.1 criteria and MDA standards. * The patient has received local therapy to primary site, including surgery, stereotactic radiotherapy, or ablation. * The patient has received no more than 2 lines of systemic therapy. * No significant impairment of major organ function: Hemoglobin (HB) ≥ 80 g/L Absolute neutrophil count (ANC) ≥ 1.5 × 10⁹/L Platelets (PLT) ≥ 75 × 10⁹/L Serum total bilirubin ≤ 1.5 × ULN Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 × ULN Prothrombin time (PT) and activated partial thromboplastin time (aPTT) ≤ 1.5 × ULN Exclusion Criteria: * Presence of intracranial metastases. * Target lesions have previously received high-dose irradiation with . * Target lesions are unsuitable for radiation therapy judged by treating radiation oncologist (e.g., lesions invading the gastrointestinal tract or penetrating the bronchus). * Uncontrollable metastatic pleural effusion or ascites. * Presence of other malignancies that have not been cured. * History of significant psychiatric disorders that impede understanding of informed consent and compliance with the study protocol. * Presence of other serious illnesses that may pose significant risks or affect radiation therapy. * Women who are pregnant, breastfeeding, or with plans for childbearing during the study. * Any other reasons deemed by the investigator to make the subject unsuitable for participation in the study.