2 The condition, current treatments and procedure
2.1 Around 30% to 50% of people with colorectal cancer have liver metastases at the time of presentation or develop them during the course of the disease.
2.2 Treatment of liver (hepatic) metastases depends on their extent and location. For unresectable tumours, treatment options include thermal ablation techniques, chemotherapy, different types of arterial embolisation therapy and external beam radiotherapy.
2.3 Selective internal radiation therapy (SIRT; also known as radioembolisation) can be used as palliative treatment for unresectable colorectal metastases in the liver.
2.4 SIRT involves delivering microspheres containing radionuclides that emit beta radiation directly into the tumour. This aims to minimise the risk of radiation damage to surrounding healthy tissue. Using local anaesthesia and fluoroscopic guidance, the radioactive microspheres are injected into branches of the hepatic artery supplying the tumour. A percutaneous approach is used through the femoral or radial artery. The microspheres lodge in small arteries within and surrounding the tumour, releasing high doses of radiation directly into it. The procedure may be repeated depending on the response.