Hepatic Tumor Radioembolization

Background and indications

Radioembolization (SIRT - Selective Internal Radiation Therapy), also called selective internal radiation therapy with yttrium-90 (Y90), involves injecting radioactive microspheres (Y90-loaded) into hepatic arteries feeding tumors. The microspheres lodge in the tumor microvasculature and deliver a targeted high-energy (beta) radiation dose to the tumor, with tissue penetration limited to 2.5-11 mm, sparing healthy liver parenchyma.

Indications include: unresectable HCC (all BCLC stages, including segmental/lobar portal vein thrombosis), chemotherapy-refractory colorectal liver metastases, and liver metastases from other primaries (neuroendocrine tumors, intrahepatic cholangiocarcinoma, uveal melanoma).

Pre-procedure assessment

Assessment involves two steps: (1) standard workup (liver MRI, TAP CT, blood panel including Child-Pugh and bilirubin) and (2) a preparatory hepatic arteriography (mapping) with technetium-99m-labeled macroaggregated albumin (MAA-Tc99m) injection into hepatic arteries to evaluate hepatopulmonary shunt (must be < 20%) and detect extrahepatic fixation (stomach, duodenum). This preparatory procedure is performed 1-2 weeks before treatment.

Procedure

Under local anesthesia and sedation, a catheter is introduced through the femoral artery. Under fluoroscopic guidance, Y90 microspheres (glass: TheraSphere® or resin: SIR-Spheres®) are slowly injected into hepatic arteries feeding the tumor lobe or segment, reproducing exactly the mapping session catheterization. Activity is calculated based on tumor and liver volume, target dose, and pulmonary shunt. The procedure takes 1 to 2 hours.

Results and scientific evidence

For HCC, the SARAH and SIRveNIB studies compared radioembolization with sorafenib. Radioembolization offers better tolerance and superior quality of life, with comparable survival (Salem et al., Gastroenterology, 2011; DOI: 10.1053/j.gastro.2010.10.004). The DOSISPHERE-01 trial showed that personalized dosing ≥ 205 Gy significantly improves response and survival (Garin et al., The Lancet Gastroenterology and Hepatology, 2021; DOI: 10.1016/S2468-1253(20)30290-9).

For colorectal metastases, the SIRFLOX trial showed improved hepatic response rate with Y90 + chemotherapy.

Risks and complications

Fatigue (50-70%), abdominal pain (20-30%), nausea (10-20%). Major complications: radiation pneumonitis (< 1% if shunt < 20%), radioembolization-induced liver disease (REILD: 2-5%, mainly on cirrhotic liver), gastroduodenal ulcer from non-target irradiation (< 3%). 30-day mortality is 1-3%.

Recovery

1-2 night hospitalization (radiation protection precautions). Return to activities in 3-7 days. Control MRI at 3 months (response is slower than after TACE).

Practical information

The procedure is performed as a short inpatient stay. It is performed by an interventional oncology radiologist, in collaboration with the nuclear medicine physician, hepatologist, and oncologist.