Embolization has been used for many years in the treatment of primary liver tumors. It uses the action of tiny particles to clog the blood vessels that feed the tumor, depriving it of the nutrients it needs to grow. These particles are often combined with a chemotherapy drug, so they are injected directly into the liver. Today, embolization therapies are increasingly used for the treatment of metastatic liver tumors, the efficacy of which is based on their ability to obstruct vessels, but above all on their effect of targeting the release of a powerful dose of drug to the liver.
Embolization therapies can be used alone or in combination with pharmacological therapies to treat metastatic tumors if surgery or ablation is not appropriate, and they may be effective in reducing liver injury so that it can be treated with surgery.
As with radiofrequency ablation, embolization is performed by an interventional radiologist, who uses special X-ray equipment to guide a catheter from a small entry hole in the groin, through blood vessels, and into the liver. The particles are then injected through the catheter. The particles can be used to deliver doses of chemotherapy or radiation therapy by:
- Transarterial chemoembolization (TACE ) delivers embolic material combined with a chemotherapy drug (usually irinotecan) directly to the liver. If the tumor cannot be removed surgically or there is no possibility of transplantation, the treatment of choice is chemoembolization. This technique consists of infusing chemotherapy drugs (which kill cancer cells), attached to spheres of inert material, into the hepatic artery. In fact, liver tumors are supplied by branches of the hepatic artery, while healthy liver tissue is supplied by another vessel, the portal vein. Precisely for this reason, the selective injection of drugs into the branches of the hepatic artery can determine the formation of an embolus or an occlusion only in the vessels that supply the tumor, limiting the toxicity for healthy tissue. The results obtained with chemoembolization are good: a significant reduction in tumor mass has been observed in 40-50% of cases; moreover, half of the treated patients survive more than a year after treatment. Candidates for chemoembolization are inoperable and unresectable patients with disease limited to the liver (single or multiple nodule HCC greater than 5 cm in size), in good general condition, and with intact liver function; Tumors classified as grade C according to Child's system are excluded.
- Transarterial Radioembolization (TARE) – uses tiny particles containing radioactive yttrium-90, which are injected directly into liver tumors, delivering radiation therapy "from the inside." TARE is also sometimes called "selective internal radiation therapy" (SIRT) treatment.