- Review
Hepatocellular carcinoma (HCC) often recruits an arterial blood supply from parasitized extra-hepatic vessels. Yttrium-90 (Y-90) radioembolization can be delivered directly through these vessels as an alternative to embolizing them to redistribute flow. This comprehensive review describes the feasibility, safety, and reported tumor response of that approach. PubMed, Embase, and Scopus were searched to June 2026, and outcomes were summarized descriptively. We included five retrospective cohorts (109 reported participants) and six case reports. All five cohorts were at serious risk of bias. The studies reported delivery through the inferior phrenic, cystic, adrenal, internal mammary, and superior mesenteric arteries. Delivery through the extra-hepatic artery was completed in every treated patient. In the four cohorts reporting tumor response, the objective response ranged from 68% to 100% and complete response from 21.1% to 76.5%, with wide confidence intervals, but nearly all patients also received hepatic-artery Y-90, so response cannot be attributed to the extra-hepatic route alone. Grade ≥ 3 toxicity occurred in 5.0% and 7.0% of patients in the two cohorts reporting it, and no radioembolization-induced liver disease was reported. No study compared direct delivery with flow redistribution, so the evidence supports feasibility and preliminary safety in selected patients rather than efficacy, and comparative studies with standardized dosimetry and reporting may be helpful.
14 November 2026




