It is generally for selected patients with surgically unresectable cancers, especially hepatocellular carcinoma or metastasis to the liver.

[citation needed] SIRT can be performed using several techniques, including whole liver treatment, lobar or segmental approaches.

The high dose results in eradication of the tumor while damage to healthy liver tissue is contained to the targeted segments only.

Results of these studies, published in 2017 and 2018, reported no superiority of SIRT over chemotherapy in terms of overall survival (SARAH,[17] SIRveNIB,[18] FOXFIRE[19]).

[20] These trials did not give direct evidence supporting SIRT as a first-line treatment regime for liver cancer.

However, these studies did show that SIRT is generally better tolerated than systemic therapy, with less severe adverse events.

Simultaneously, for HCC, data derived from a large retrospective analysis showed promising results for SIRT as an earlier stage treatment, particularly with high dose radiation segmentectomy and lobectomy.

The therapeutic effect of all three types is based on local deposition of radiation dose by high-energy beta particles.

[29] 90Y's low bremsstrahlung photon and positron yield make it difficult to perform quantitative imaging.

[31] 1.85 (50.0%) Theraspheres (glass 90Y microspheres) are FDA approved under a humanitarian device exemption for hepatocellular carcinoma (HCC).

[37] QuiremSpheres (PLLA 166Ho microspheres) received their CE mark in April 2015 for treating unresectable liver tumors and are currently only available for the European market.

Extrahepatic vessels found on angiographic evaluation can be embolized, to prevent nontarget deposition of microspheres, that can lead to gastrointestinal ulcers.

[47] After treatment, for 90Y microspheres, bremsstrahlung SPECT or PET scanning may be done within 24 hours after radioembolization to evaluate the distribution.

Complications due to extrahepatic deposition include radiation pneumonitis, gastrointestinal ulcers and vascular injury.

[48] Postradioembolization syndrome (PRS) includes fatigue, nausea, vomiting, abdominal discomfort or pain, and cachexia, occurring in 20-70% of patients.

[49] REILD is characterized by jaundice, ascites, hyperbilirubinemia and hypoalbuminemia developing at least 2 weeks-4 months after SIRT, absent tumor progression or biliary obstruction.

In the 1980s, the safety and feasibility of resin and glass yttrium-90 microsphere therapy for liver cancer were validated in a canine model.

More recently, larger trials and RCTs have shown safety and efficacy of 90Y therapy for the treatment of both primary and metastatic liver malignancies.

[52] Since then, several trials have been performed showing safety and efficacy of 166Ho SIRT,[53] and more studies are ongoing.