Surgery vs. Watch-and-Wait Strategy in Complete Responders for Hepatocellular Carcinoma (SWITCH)

Inclusion Criteria:

1. Aged 18-80 years.
2. Diagnosed with locally advanced, metastatic, and/or initially unresectable hepatocellular carcinoma (uHCC) via histology/cytology or clinical criteria (AASLD standards for cirrhotic patients; histopathological confirmation required for non-cirrhotic patients).
3. Previously judged unresectable or inappropriate for resection by MDT during initial diagnosis or disease course, with at least one evaluable lesion per RECIST v1.1.
4. Completed conversion therapy \[systemic therapy (PD-1/PD-L1 ± TKI) ± local therapy (TACE/HAIC/radiation/ablation, etc.)\], achieved CR or PR (primarily assessed by mRECIST, with concurrent RECIST v1.1 documentation), and confirmed via re-evaluation with the same imaging modality ≥4 weeks later.
5. Meets necessary conditions for resection: Child-Pugh Class A liver function, ICG R15 \<30%, and future liver remnant (FLR) accounting for ≥40% of standard liver volume (SLV) in patients with chronic liver disease, hepatic parenchymal injury, or cirrhosis, or ≥30% in patients without liver fibrosis or cirrhosis.
6. For patients with previous portal vein/hepatic vein/inferior vena cava tumor thrombus (without atrial tumor thrombus), enrollment is permitted only if the thrombus has significantly regressed after conversion therapy, MDT confirms feasibility of R0 resection, and risks are acceptable.
7. ECOG performance status 0-1.
8. Adequate organ and bone marrow function, as evidenced by: hemoglobin ≥90g/L; absolute neutrophil count ≥1.5×10⁹/L; platelets ≥60×10⁹/L; total bilirubin ≤1.5×upper limit of normal (ULN); AST, ALT, and ALP ≤2.5×ULN; serum creatinine ≤1.5×ULN or estimated creatinine clearance ≥50ml/min (Cockcroft-Gault formula); urine protein \<(++) or 24-hour urine protein \<1.0g.
9. Normal coagulation function without active bleeding: INR ≤1.5×ULN; APTT ≤1.5×ULN.
10. For patients with active hepatitis B virus (HBV) infection: those already receiving anti-HBV therapy (per local standard treatment) must agree to continue during the study; those not receiving anti-HBV therapy must initiate treatment (per local standard treatment) during screening and agree to continue throughout the study.
11. For patients with HCV infection: excluded if HCV RNA is detectable.
12. No pregnancy or pregnancy plans: fertile females must have a negative urine/serum pregnancy test within 7 days before first dosing and agree to use effective contraception during the study and for 120 days after last dosing; non-sterilized males must agree to use effective contraception during the study and for 120 days after last dosing.

Exclusion Criteria:

1. Known fibrolamellar HCC, sarcomatoid HCC, or mixed cholangiocarcinoma-HCC.
2. Extrahepatic metastasis confirmed by chest, abdominal, and pelvic CT and/or MRI.
3. Inability to achieve R0 resection.
4. Previous liver transplantation or on the liver transplantation waiting list.
5. Decompensated cirrhosis (persistent or refractory ascites, hepatic encephalopathy, progressive jaundice, etc.); Child-Pugh Class B with score ≥8 or Class C; ALBI Grade 3.
6. Significant and uncontrollable portal hypertension (e.g., markedly elevated HVPG with recurrent variceal bleeding, refractory ascites).
7. Active gastrointestinal bleeding within the past 4 weeks or uncorrectable coagulation disorders.
8. Active infection/sepsis or unresolved Grade ≥2 immune-related adverse events (irAEs).
9. Severe cardiopulmonary/renal insufficiency (e.g., NYHA Class III-IV, recent myocardial infarction/stroke, dialysis dependency).
10. Pregnancy or lactation.
11. Other active malignant tumors within the past 5 years (exceptions for low-risk tumors such as basal cell carcinoma of the skin or carcinoma in situ of the cervix).
12. Inability to undergo standardized imaging assessments (multiphase contrast-enhanced CT/MRI) or poor compliance.