SBRT Plus Systemic Therapy vs Systemic Therapy Alone in BCLC C Hepatocellular Carcinoma

Inclusion Criteria: 1. Age 18-70 years. 2. Histologically or clinically diagnosed HCC per national guidelines. 3. BCLC stage C (CNLC IIIA/IIIB), including PVTT and/or extrahepatic metastases amenable to protocol procedures. 4. Child-Pugh class A or B (score ≤7). 5. At least one measurable lesion per RECIST 1.1 (criteria specified). 6. ECOG ≤2. 7. Expected survival ≥6 months. 8. Adequate organ function per protocol thresholds. 9. For experimental arm candidates: active lesion count (when PET-CT used) ≤10. 10. If prior initial systemic therapy given: intrahepatic disease stable ≥3 months. 11. Effective contraception from consent through 1 year after treatment end. 12. Ability to understand and sign consent. Exclusion Criteria: 1. Second primary malignancy (exceptions apply). 2. Tumor thrombus/metastases judged not amenable to radiotherapy. 3. Prior systemic anticancer therapy for current HCC (prior local therapy permitted per rules). 4. Severe organ dysfunction precluding treatment. 5. Uncontrolled comorbidities (e.g., uncontrolled diabetes, active peptic ulcer, severe cardiopulmonary disease). 6. Active uncontrolled infection or active autoimmune disease requiring systemic therapy. 7. Significant neurologic dysfunction. 8. Pregnant or breastfeeding women; no effective contraception. 9. Known hypersensitivity to planned drugs. 10. Any other condition making participation unsuitable per investigator.