Transarterial Treatments

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The second group of minimally invasive interventions in cancer patients are transarterial treatments. These treatments are performed by placing a tiny catheter from the groin into the feeding arteries of the tumor (selective catheterization). To do this, special angiography machines are used, which are different from the ones used in coronary angiography.

How are they done?

For transarterial treatments, first the patient is put on the angiography table, the groin is disinfected and numbed with local anesthetic, and a small tube (sheath) is placed into the groin artery. Then, a tiny catheter is inserted through this tube and advanced to the region where the tumor is located. After that, multiple angiography films are taken to identify the feeding arteries of the tumor.

In some centers like ours, special angiography devices equipped with a “cone beam CT” are present, which can generate both angiography and computed tomography images simultaneously in 3 dimensions. With such devices, it is possible to idelinesntify the feeding arteries of tumors much more easily and accurately. After these arteries are seen on the angiography screen, special catheters are placed into these vessels and transarterial treatments are performed.

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What transarterial treatments are performed?

Once the feeding arteries of the tumor are catheterized, four kinds of transarterial treatments can be performed.

  • Intraarterial chemotherapy: In this method, chemotherapeutic drug is infused directly into the feeding arteries of the tumor. In standart chemotherapy, the drug is given through the arm vein or a chest port, and it first goes to the lung and heart. Then, it is pumped by the heart to all over our body. Thus, when the drug reaches the tumor, its concentration is very decreased since it is mixed with the blood during that time. In contrast, when chemotherapeutic drug is infused directly into the tumor’s feeding arteries, it is not mixed with the blood and its concentration is not decreased.

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Intraarterial chemotherapy is mostly performed for cancers located in the neck, eye, head, liver, breast, lung and extremities (arms and legs).
Transarteryel-Tedaviler-3It is generally done via angiographies performed with 1-3 weeks intervals. Transarteryel-Tedaviler-4If the chemotherapy is planned for a long time or the patient does not want to undergo angiography frequently, an arterial port catheter can also be implanted. In this technique, a soft catheter is placed into the feeding vessels via angiography, and the other end of the catheter is attached to a small reservoir (port), which is then implanted beneath the skin at the groin. In this way, intraarterial chemotherapy can be performed whenever needed via the arterial port, instead of doing an angiograpy in each session. Arterial ports can be used for months or even for years unless they are occluded or infected. These ports are mostly used for the intraarterial chemotherapy of primary and metastatic liver tumors.

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Transarteryel-Tedaviler-6Another form of intraarterial chemotherapy is “isolated limb infusion” (ILI). This technique can be used in tumors located solely in an arm or leg. For ILI, first the artery and vein of the extremity are punctured and a catheter is placed into each vessel. Then, a tourniquet is applied to the arm or leg, and the extremity is isolated from the systemic circulation. During the infusion, the blood is aspirated from the vein, mixed with a high dose chemotherapeutic agent (melphalan), warmed to 40-42 degrees and injected into the artery of the extremity. This process is repeated continuously for 20-30 minutes and the extremity is exposed to a very high dose intraarterial chemotherapy. Since the drug dose not pass to the systemic circulation, there is very mild or no side effects, and thus, the concentration of the chemotherapeutic drug can be increased to 20-100 times than the normal. ILI is mostly employed for the skin metastases of malignant melanoma and special soft tissue tumors called sarcoma. Transarteryel-Tedaviler-7

  • Embolization: Embolization means intentional obstruction of the feeding arteries of a tissue or organ. The goal of embolization is either to kill the tissue (necrosis) or to reduce its blood supply (ischemia). In general, necrosis occurs only if the tiny arteries (capillaries) of the tissue are occluded, and this can be achieved by using very small (<50 microns) particles or liquid embolising agents such as alcohol. If embolization is done by using large particles, the tissue generally will not die but its blood supply will be decreased (ischemia). Transarteryel-Tedaviler-8The results of embolization may be different in benign versus malignant tumors. In benign tumors, embolization can easily kill the tissue even if relatively large particles are used. For example, benign uterine tumors called fibroids can be easily killed in one session with embolization and the patient is cured permanently. In contrast, malignant tumors are more resistant to embolization since they release some substances that stimulate new feeding vessel formation. For this reason, even if they are embolized successfully, malignant tumors (cancers) can keep their viability, unless very small particles or liquid agents are used. However, since embolization reduces their blood supply, the problems due to tumor such as bleeding or pain may diminish or disappear after the embolization. Since embolization alone is rarely enough to kill the cancer tissue, other forms of embolization such as chemoembolization or radioembolization are more commonly performed in cancer treatments.

 

  • Chemoembolization: This technique is a combination of intraarterial chemotherapy and embolization, and has the potential to kill the cancerous tissue. There are two kinds of chemoembolization techniques. In “classic” chemoembolization, the chemotherapeutic drug is mixed with embolizing particles and lipiodol, a substance that tumor cells like, and injected into the feeding vessels of the tumor. The mixture is taken up by the tumor tissue much more than the normal tissue and the feeding vessels are occluded by the particles. As a result, the chemotherapeutic drug stays in the tumor for a long time, and this effect, combined with the embolization, may kill the cancerous tissue completely.Transarteryel-Tedaviler9The other chemoembolization technique uses the drug-eluting particles instead of the drug+lipiodol+particles mixture. In this technique, first the chemotherapeutic drug is absorbed by the specially produced small particles, and then it is injected into the feeding arteries of the tumor. In this way, the feeding vessels are occluded by these particles, which also release the chemotherapeutic drug for days or weeks. As a result, the combined effect of embolization and highly concentrated chemotherapeutic drug released by the particles kill the tumor completely. Today, both chemoembolization techniques are successfully used in liver tumors, especially in colon cancer metastases and a primary liver tumor called hepatocellular carcinoma (HCC).Transarteryel-Tedaviler-10
  • Radiooembolization (Y90 microsphere treatment): This method is a combination of embolization and “internal” radiotherapy and also has the potential to kill the cancerous tissue. In radioembolization, first a radioactive material (Y90) that emits beta radiation is loaded into very tiny particles and then these particles are injected into the tumor’s feeding arteries. In this way, not only these arteries are occluded and the tumor’s blood supply is reduced, but also the tumor cells are exposed directly to a very high dose of radiation. In standart radiotherapy, radiation is given from an external source and has to pass the surrounding organs to reach the tumor. Since it may also harm the surrounding organs, there is a certain limit for radiation dose that can be given to the patient. In contrast, the beta radiation used in radioembolization is effective in only a 2.5 mm distance, and thus, it affects only the tumor it is injected and does not harm the surrounding healthy tissue. For this reason, it can be applied at a much higher dose than the standart radiotherapy. Like chemoembolization, radioembolization is also used for the treatment of primary and metastatic liver tumors.
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What are the advantages and disadvantages of transarterial treatments?

The most important advantage of transarterial treatments is their increased local effect to the tumor, since they are done directly via the feeding vessels, and decreased systemic side effects, since other tissues or organs are not affected. For example, in intraarterial chemotherapy, the drug concentration in the tumor is about 10-20 times higher than in systemic chemotherapy, and thus, its tumor-killing effect is much higher but side effects to other organs are fewer. Likewise in embolization, chemoembolization and radioembolization, only the tissue fed by the embolized vessels is affected, and other tissues or organs are not harmed. On the other hand, transarterial therapies require multiple sophisticated angiography sessions. To do this, a special angiography device, which is totally different from the one used in cardiology, and a well-trained staff are necessary. For this reason, transarterial cancer treatments are performed in a limited number of centers worldwide.

What factors affect the treatment results?

Although they have the potential to kill the cancerous tissue, transarterial treatments are less likely to achieve complete destruction of the tumor compared to percutaneous ablation methods. For this reason, if the tumor is suitable for surgery or percutaneous ablation they must be the first choice treatments. However, transarterial treatments can be effective in a larger area than these therapies, therefore, they can be used in larger and multiple tumors, which are not suitable for surgery or percutaneous ablations. In such cases, transarterial treatments can decrease the number and size of the tumors and make them suitable for percutaneous ablation or surgery, or they can increase the survival and life quality of the patient. In most patients, classic chemotherapy and/or radiotherapy are first tried, and if they are not sufficient, then transarterial treatments are performed alone or in combination with these classic therapies.

For the success of transarterial treatments, the vascular structure of the tumor is important. In general, cancers with an increased blood supply and vascularity respond better to transarterial treatments. Besides, a single feeding vessel versus multiple feeders, and straight-large arteries versus tiny and tortuous arteries are favorable, because it is technically easier to place a catheter into such vessels.

The most commonly performed transarterial treatment is intraarterial chemotherapy. This treatment can be applied to any region that can be reached with a microcatheter. However, it is more frequently performed for tumors located in the liver, eye, head, neck, brain, lung, breast, pancreas and extremities. Similarly, embolization can also be applied to any tumor that can be reached with a microcatheter. However, the use of chemoembolization and radioembolization is more limited. Although the use of chemoembolization has been described in many tumors outside the liver, and radioembolization has been successfully used in the kidney and spleen, the application of both techniques to tumors located outside the liver is considered experimental at present.

What kind of tumors are most suitable for transarterial treatments?

• All kinds of primary and metastatic liver tumors.
• Locally advanced inoperable lung tumors that have a few or no distant metastases.
• Tumors located in other organs, that may become suitable for ablation or surgery, if reduced in size or number with transarterial treatments.

Interventional Treatments