Selective Internal Radiation Therapy for Hepatocellular Malignancies: Existing Evidence and Advances

Selective Internal Radiation Therapy (SIRT) is a locoregional treatment for primary and secondary liver neoplasms that spares the surrounding parenchyma while selectively delivering a high radiation dose to the tumour tissue. It functions by injecting radioactive microspheres into the hepatic artery supplying the tumour. SIRT has emerged as a valuable locoregional treatment for liver cancers, including unresectable hepatocellular carcinoma (HCC) and some liver-dominant metastases, such as neuroendocrine tumours and chemo-refractory colorectal cancer. SIRT involves the intra-arterial delivery of radioactive microspheres, most commonly yttrium-90 ( 90 Y). This review summarises the current status of SIRT, including its principle, patient selection criteria, treatment planning, clinical outcomes, safety profile, and future prospects. Major clinical trials such as SARAH, SIRveNIB, LEGACY, and DOSISPHERE-01 have established the role of SIRT across different stages of HCC, demonstrating favourable tumour response rates and improved quality of life. However, the overall survival benefits compared to systemic therapy remain limited. Advances in personalised dosimetry, artificial intelligence-assisted treatment planning, and post-therapy imaging are enhancing treatment precision. Emerging radionuclides such as 166 Ho and 188 Re, alongside the development of indigenous microspheres, may improve accessibility and cost-effectiveness, particularly in resource-limited settings. Continued technological innovation, clinical research, and infrastructure development are expected to strengthen the integration of SIRT into the multidisciplinary management of unresectable liver cancer.