Yttrium-90 glass microsphere radioembolization as frontline treatment for hepatocellular carcinoma with localized portal vein invasion.

[OBJECTIVES] To evaluate the outcomes of yttrium-90 radioembolization (glass microspheres) in patients with unilobar hepatocellular carcinoma (HCC) and portal vein invasion (PVI) who have preserved liver function.

[MATERIALS AND METHODS] This study included 48 patients with unilobar HCC and PVI, all with Child-Pugh A, treated with radioembolization at a single institution between January 2016 and December 2023. Tumor response was assessed using the modified Response Evaluation Criteria in Solid Tumors (mRECIST) and localized mRECIST. Overall survival (OS) and prognostic factors were evaluated using time-to-event analyses. The mean tumor absorbed dose (TAD) threshold for achieving complete response (CR) by localized mRECIST was determined using receiver operating characteristic analysis, while the threshold associated with significantly longer OS was identified using the minimum p-value approach.

[RESULTS] Objective response rates were 83% (40/48) by mRECIST and 88% (42/48) by localized mRECIST. The median OS was 47.2 months (95% CI, 19.1-52.1 months). The TAD was the only significant predictor of OS (p = 0.032, hazard ratio = 0.862 per 100 Gy, 95% CI = 0.753-0.988). A mean TAD > 574 Gy provided 50% sensitivity and 86% specificity for predicting CR by localized mRECIST, while a threshold of 586 Gy was proposed to significantly extend OS (median OS, 49.5 months for > 586 Gy and 21.9 months for ≤ 586 Gy; p = 0.021).

[CONCLUSION] Radioembolization is effective for HCC with localized PVI in patients with preserved liver function, and a mean TAD > 600 Gy is proposed to achieve improved oncologic outcomes.

[KEY POINTS] Question What is the optimal radioembolization approach and its outcome for hepatocellular carcinoma with localized portal vein invasion (Vp1-3) in patients with preserved liver function? Findings A tumor absorbed dose exceeding 600 Gy via a tandem approach achieved complete response rates above 80% and median overall survival longer than 49.5 months. Clinical relevance Ablative radioembolization, delivering a tumor absorbed dose exceeding 600 Gy via a tandem approach, should be considered for hepatocellular carcinoma with localized portal vein tumor thrombosis (Vp1-3) in patients with preserved liver function and no extrahepatic spread.