Adjuvant Radiotherapy of Sintilimab Versus TACE for HCC

Inclusion Criteria: 1. R0 resection of hepatocellular carcinoma (HCC) with a surgical margin \<1 cm (determined by postoperative pathology, surgical records, and imaging). 2. Within 4 months after curative resection. 3. High-Risk Recurrence Factors (at least one required in addition to narrow margin): (1) Microvascular invasion (MVI) positive, tumor thrombus, or satellite nodules (2) Preoperative AFP \>400 ng/mL (3) Tumor \>5 cm with incomplete capsule 4. ≥18 and ≤80 years old. 5. ECOG score 0-1. 6. Child-Pugh Class: A5, A6, or B7. 7. Postoperative Contrast-enhanced MRI of the liver must be performed to exclude intrahepatic residual lesions. 8. HBV DNA and HCV RNA status do not affect eligibility, but if HBV DNA positive and/or HCV RNA positive: ALT must be \<1.5× upper limit of normal (ULN). Antiviral therapy must be initiated. 9. Liver Function Tests (LFTs): ALT ≤2.5× ULN (if HBV/HCV positive, ALT ≤1.5× ULN). If ALT ≤1.5× ULN, AST ≤6× ULN (excluding AST elevation due to myocardial infarction). If ALT 1.5-2.5× ULN, AST ≤2.5× ULN. 10. No significant ECG abnormalities and no severe cardiac dysfunction. 11. Serum creatinine (CRE) and BUN ≤2.5× ULN. 12. Hb≥80g/L，ANC≥1.0×109 /L，PLT≥40×109 /L. 13. Written informed consent obtained. Exclusion Criteria: 1. Vp3 or Vp4 portal vein tumor thrombus (PVTT) or Vv2/Vv3 inferior vena cava (IVC) tumor thrombus on preoperative imaging. 2. Previous anti-HCC therapies, including but not limited to: targeted therapy (e.g., tyrosine kinase inhibitors), immune checkpoint inhibitors (e.g., PD-1/PD-L1 inhibitors) or systemic chemotherapy 3. Distant metastasis before randomization. 4. Moderate to severe ascites unresponsive to medical management. 5. History of other malignancies, except: carcinoma in situ，early-stage papillary thyroid cancer or basal cell carcinoma of the skin 6. Previous radiotherapy involving the abdomen. 7. Significant cardiac, renal, or other major organ dysfunction. 8. Active Autoimmune Disease or Psychiatric Disorders. 9. HIV Infection. 10. Pregnant or breastfeeding women. 11. Currently enrolled in another interventional clinical trial.