Intrahepatic or "Regional Therapies"

Radiofrequency Ablation

Radiofrequency ablation (RFA) involves the insertion of a needle/probe from the skin into the liver tumor:

This is accomplished under direct CAT scan (CT) or ultrasound (US) guidance.
Once the tip of the probe is in the tumor, a radiofrequency generator is connected to it and activated.
Over the next few minutes, the temperature of the tumor around the probe increases until it reaches lethal levels. The objective is to kill the entire tumor while minimizing any collateral injury to the liver.
The procedure is performed under sedation and on an outpatient basis. Occasionally a one night hospital stay may be necessary.

Studies have shown that RFA can be very effective in treating liver tumors, and under certain circumstance can be as effective as surgery. This is especially true for smaller tumors (< 3 cm). Additionally, RFA can be used to treat lesions in patients who cannot have surgery because of other medical problems or in conjunction with surgery.

The figure on the left shows the probe (red arrows) entering the skin and traversing the liver. The tines are opened in the shape of an umbrella (circle) where localized heat kills the tumor.

Regional or Intra-hepatic Therapy

Regional or Intra-hepatic Therapy involves the liver receiving blood from two blood supplies:

The hepatic artery comes from the heart and supplies blood rich in oxygen.
The portal vein brings blood that is rich in nutrients absorbed from the small intestine.
These vessels divide into smaller and smaller vessels, ending in capillaries. These capillaries end in the thousands of lobules of the liver.
Each lobule is composed of hepatocytes (liver cells), and as blood passes through, they are able to add and remove substances from it.
The hepatocytes remove drugs, alcohol, and nutrition from food, and process these substances for use or removal by the body.
The “cleaned” blood then leaves the liver via a third blood supply, the hepatic vein, returns to the heart, and is ready to be pumped to the rest of the body.
When HCC forms in the liver they get their blood supply almost exclusively, from the branches of the hepatic artery.
Regional therapies take advantage of this fact and deliver therapy into the hepatic artery and directly into the tumor.

Regional therapy may be appropriate for patients with tumors that are located only in the liver which are unable to be removed by surgery. Some liver tumors tend to grow into the portal vein, causing portal vein thrombosis (PVT). Depending on the extent of tumor in the portal vein, liver directed therapy may not be a safe and effective option. PVT can often be seen on routine CT or MRI imaging of the liver.

The hepatic artery can be reached by placing a needle into the large common femoral artery in the groin. A thin catheter is then advanced using radiographic guidance through the femoral artery, into the abdominal aorta, through the celiac axis and common hepatic artery and into the proper hepatic artery. Therapy injected into the catheter is delivered directly into the tumor. Multiple therapies have been delivered in this way.

Chemotherapy

Chemotherapy can be infused in very concentrated doses directly into the liver tumor. However, when used alone, chemotherapy infused this way is quickly absorbed into the body and can cause the usual side effects associated with chemotherapy. Lipiodol is an oily agent that is preferentially picked up by liver cells and has been used with chemotherapy to keep therapy concentrated in the tumor.

Embolization

Embolization is the placement of small particles into the small vessels that feed the tumor preventing blood flow into the tumor. Transarterial chemoembolization (TACE) delivers a mixture of chemotherapy, often with lipiodol followed by particles that block the blood vessels feeding the tumor. Radiomicrospheres are a different approach that delivers radiation directly into the tumor using tiny microscopic spheres embedded with a special type of radiation.

Transarterial chemoembolization is performed by a special type of doctor known as an interventional radiologist.

The advantage of TACE is that higher concentrations of chemotherapeutic agents can be delivered directly to the tumor cells without subjecting the patient to the systemic effects. However, as with any chemotherapeutic agent, systemic side effects can still occur.
Not all patients are candidates for chemoembolization, as there are limiting factors that prevent patients from undergoing this type of treatment.
Patients with large portal vein thrombosis, obstruction of the biliary system, or large amount of ascites, are not candidates for TACE. Other conditions such as severely elevated bilirubin, low platelets, elevated liver enzymes, cardiac or kidney disease also must be carefully considered.
Prior to the TACE procedure, doctors will give a patient liver function tests, kidney tests and blood clotting tests. On the day of the procedure the interventional radiologist will perform an angiogramof the liver in which contrast dye is injected into the hepatic artery to identity the blood supply to the tumor. They may identify small blood vessels that deliver blood to the gall bladder, intestine or stomach. By blocking these blood vessels with embolic agents, they can prevent the chemotherapy from passing to these areas and causing side effects.

The interventional radiologist will then inject the material - in most cases in liquid form. Following the injection, they will remove the catheter from the femoral artery and apply pressure to seal the artery.

As with any interventional procedure, there is a small risk of a bleeding, bruising or infection at the injection site in the groin. Less common but more serious side effects include inflammation of the gallbladder (cholecystitis), intestinal and stomach ulcers, and inflammation of the pancreas (pancreatitis). Rarely an infection or abscess may occur at the site in the liver of the killed tumor. Patients with advanced cirrhosis may develop liver failure after this treatment.

The TACE procedure is relatively safe, with the most common side effects being abdominal pain, low-grade fever, fatigue, flu-like symptoms, and decreased appetite (post-embolization syndrome) for 1-2 weeks. It is common for patients to stay in the hospital for 24 hours to monitor the elevation of their liver enzymes, and for other supportive care. When discharged, patients are provided with prescriptions for antibiotics and medications for nausea and pain. A few weeks following the therapy, the doctor will order a CT scan or MRI to evaluate the response to the therapy. More than one treatment may be needed to control the tumor.

Radiolabelled Microspheres

Radiolabelled microspheres (also called brachytherapy) has been shown to be an effective treatment for liver cancer with an improvement in pain and other symptoms.

Microspheres are small beads made of a polymer or glass that are embedded with yttrium-90, a radioisotope that emits beta-radiation.
The radiomicrospheres are delivered to the tumor by placing a catheter into the femoral artery in the leg and, under radiographic guidance, passing the catheter up to the hepatic artery in the liver that is feeding the tumor.
The microspheres are infused and become lodged in the small capillaries within the tumor. Radiation is then released slowly from the beads and radiates the tumor from the inside out.

The procedure is very similar to TACE, although additional tests are required beforehand to determine if a patient is a good candidate for radiolabelled microspheres (also called brachytherapy). Several tests are used to determine the safety and dose of radiation that can be infused.

The interventional radiologist will perform an angiogram of the liver in which contrast dye is injected into the hepatic artery to identity the blood supply to the tumor. They may identify small blood vessels that deliver blood to the gall bladder, intestine or stomach. By blocking these blood vessels with embolic agents, they can prevent the radiomicrospheres from passing to these areas and damaging normal tissue.

The interventional radiologist will then perform a macro aggregated albumin scan (MAA scan). The MAA is a small protein particle with the technetium-99 isotope embedded in it. Technetium-99 releases electromagnetic energy, like X-rays, and identifies the amount of blood that is being shunted from the liver to the lungs.

This test allows physicians to calculate the amount of radiation the lungs may be exposed to and determine if this procedure is safe. The interventional radiologist, nuclear medicine radiologist and the primary oncologist will review the results of these studies. If this treatment is felt to be appropriate and safe, the radiomicrospheres will be ordered and the treatment will be scheduled.

On the day of treatment, the catheter will be placed into the femoral artery and passed to the hepatic artery as before.
The radiomicrospheres will then be infused into the tumor.
The catheter will be removed and pressure will be held at the injection site.

Yttrium-90 decays to zirconimum-90, which is stable, by emitting beta radiation, which treats the tumor. The beta radiation extends for 2.5 mm and lasts for 10-12 days. Since the radiation penetrates a short distance, there are no special precautions necessary after infusion of the radiomicrospheres. Frequent side effects, which have occurred with radiomicrospheres, include mild nausea, pain at the tumor site and fever.

As with any interventional procedure, there is a small risk of a bleeding, bruising or infection at the injection site in the groin. Less common but more serious side effects include inflammation of the gallbladder (cholecystitis), intestinal and stomach ulcers, and inflammation of the pancreas (pancreatitis). Rarely an infection or abscess may occur at the site in the liver of the killed tumor. Patients with advanced cirrhosis may develop liver failure after this treatment, and should not receive branchy therapy.

Last Updated on 10/10/2011 10:17:28 AM