Development and Prospective Validation of a Heterogeneous Treatment Effect-Based Decision Model for Transarterial Chemoembolization Combined With or Without Atezolizumab Plus Bevacizumab in Unresectable Hepatocellular Carcinoma

Inclusion Criteria:

* • Aged≥18 years

  * Initiated first-line Atezo+Bev.
  * Eligible for TACE treatment or received at least one TACE within ±2 months of Atezo+Bev initiation (before Atezo+Bev start, anytime during Atezo+Bev therapy, or after Atezo+Bev discontinuation).
  * Clinically or pathologically diagnosed uHCC before or at the initiation of Atezo/Bev.The evidence of being diagnosed as "unresectable" may include but is not limited to below:

"Unresectable" or "advanced" directly documented in the medical records History of extrahepatic metastasis as evidenced clinically or by radiology, histology or cytology OR China Liver Cancer (CNLC) Stage IIIb

* At least one visit record after the initiation of Atezo+Bev
* No prior systemic therapy for HCC, especially immunotherapy
* No prior locoregional therapy to the target lesion(s)
* At least one measurable untreated lesion
* ECOG Performance Status of 0-2

Exclusion Criteria:

* • Evidence of extrahepatic spread (EHS)

  * Participating in interventional clinical trials.
  * Being a candidate for curative treatments
  * Any condition representing a contraindication to TACE as determined by the investigators
  * Active or history of autoimmune disease or immune deficiency
  * Untreated or incompletely treated esophageal and/or gastric varices with bleeding or high risk for bleeding
  * A prior bleeding event due to esophageal and/or gastric varices within 6 months prior to initiation of study treatment
  * Evidence of bleeding diathesis or significant coagulopathy
  * Missing critical baseline or outcome data