Embolization means angiographic occlusion of the feeding vessels of a tissue or organ in the body, and it has been used for various purposes in medicine for nearly 50 years. For example today, a bleeding in the stomach or lung can be detected by angiography, and the artery that feeds this area can be clogged with a small piece of wire and the bleeding can be stopped immediately without surgery. Or, uterine fibroids can be treated by occluding their feeding arteries (UFE), and prostate enlargement (benign prostatic hypertrophy) can also be treated with embolization without surgical operation. In the embolization treatment, the feeding arteries are blocked and the harmful tissues will shrink as their blood supply decreases, whereas the normal tissues maintain their vitality.
In cancer, embolization alone is generally not sufficient, since the remaining cancer tissue rapidly produces alternative vessels and continue to grow. Therefore in cancer, embolization is generally used in combination with intraarterial chemotherapy or intraarterial radiotherapy. In both cases, the resulting binary effect is lethal to cancer cells. Chemoembolization or TACE (transarterial chemoembolization) is a treatment modality that combines intraarterial chemotherapy with embolization and is now widely used in some types of cancer. Chemoembolization was first used in hepatocellular carcinoma (HCC), one of the primary cancers of the liver, has been highly successful and has entered the classical treatment guidelines years ago. Nowadays, according to the criteria of Barcelona (BCLC), which is accepted as a worldwide reference, chemoembolization is one of the two standard treatment modalities for intermediate stage HCC.
Following the good results obtained in the treatment of HCC, chemoembolization was also tried in liver metastases of different origin. For example, it has been successfully utilized in the liver metastases of neuroendocrine tumors (NET) from the gastrointestinal tract and is now included in all treatment guidelines. Since patients with NET usually survive for many years, chemoembolization can often be applied more than once in these patients, or it can be used in a specific order with other methods of treatment such as lutetium treatment or radioembolization. Another common area of chemoembolization is liver metastases of the large intestine. Some studies have shown that chemoembolization + classical chemotherapy may extend survival by two times more than classical chemotherapy alone.
Chemoembolization has been used successfully in other liver tumors besides these common applications. Currently, both chemoembolization and radioembolization are widely used in the bile duct cancer of liver (cholangiocarcinoma). In addition, chemoembolization has an important role in the rare vessel-rich tumors of the liver (hemangioperisitoma, hemangioblastoma, etc.) and other liver metastases (breast, kidney cancer, etc.).
Side effects (complications): After chemoembolization, the majority of patients present with abdominal pain, nausea, fatigue and fever (postembolization syndrome), which can last for 3-4 days. In addition, rare complications such as bile duct damage, abscess and liver failure may occur after chemoembolization. These complications are more common in patients with bile duct obstruction, those with stent in the bile duct and those with impaired liver function. Therefore, it is of great importance to select patients correctly to obtain good results.
There are two different types of chemoembolization (TACE) application: 1. Lipiodol-TACE and 2. DEB-TACE. The classical chemoembolization method, Lipiodol-TACE, was first developed in Japan in the 1980s. In this method, chemotherapeutic drugs are mixed with lipiodol, a special oily contrast material that is attracted by tumor cells in the liver, and then injected into the tumor arteries. Since the mixture is largely retained by tumor cells, it kills tumors and causes less damage to normal liver tissue. In order to increase the tumor-killing effect, the feeding vessels are clogged with small particles (embolization) immediately after the mixture is injected so that the mixture remains in the tumor much longer. The most important advantage of lipiodol-TACE is that the lipiodol substance is retained much more in the tumor cells and the mixture can be used with any chemotherapy drug.
DEB-TACE is derived from the initials of the English word "Drug Eluting Beads" and is a new type of chemoembolization. In DEB-TACE, chemotherapy drugs are loaded into particles prepared from special substances with diameters smaller than 1 mm. After this procedure, which lasts about 2 hours, the particles are fed into the veins feeding the tumor. These particles clog the arteries that supply the tumor and slowly release the loaded drug into the tumor for several weeks. Thus, tissue death (necrosis) occurs due to both the occlusion of the vessels and high intensity chemotherapy.
Both types of chemoembolization are now widely used in the liver. There is not enough literature data on which type of chemoembolization method is better for which type of tumor.
Interventional oncology in cancer management
Prof Saim Yilmaz, MD