Liver Ablation Therapy for Cancer Treatment

Ablation therapy is a type of liver cancer treatment that involves the use of extreme heat or cold, or chemicals to kill cancer cells. The aim of liver ablation procedures is to destroy tumors without having to remove them surgically, as not all patients are healthy enough to undergo major surgery. Together with embolization and radiation, it is also known as a locoregional treatment or interventional procedure.

This treatment is typically performed by a trained specialist called an interventional radiologist in an interventional radiology suite or sometimes in an operating room. Regardless of the type of ablation therapy, your radiologist will first use an imaging technique, such as a computed tomography (CT) scan or ultrasound, to locate the liver tumor and guide the insertion of a needle probe into the tumor. These probes are connected via cords to a generator that supplies heat, cold or chemicals.

Liver ablation therapy can be used in people with a few small tumors, for whom tumor excision (by surgical resection or transplant) is not feasible, either due to poor health or poor liver function. It is most suitable for liver tumors that are not larger than 3 cm in diameter.

For larger tumors (3 to 5 cm across), your radiologist may use ablation in conjunction with embolization. Alternatively, they may need to perform multiple ablations, which is done by repositioning the needle probe or placing multiple needles into different parts of the tumor, to ensure that no tumor tissue remains. Multiple tumors can also be treated at the same time.

While surgery still offers the best chance of cure, liver ablation therapy can help in destroying tumors and preventing further cancer growth. It may not remove the tumors, but it can lead to complete remission. For small tumors, several studies show liver ablation is as good as surgery.

In some instances, it is also used in people waiting for a liver transplant and whose tumor has to be small enough to meet the transplant eligibility criteria (known as bridging therapy). However, because this treatment often destroys some healthy tissue surrounding the tumor, it may not be the best choice for treating tumors that are located near major blood vessels, bile ducts, the diaphragm or other intra-abdominal organs.

There are a few types of ablation used to treat liver cancer. The type of liver ablation therapy that is most suitable for you will depend on factors like the extent and makeup of your liver tumor and your overall health.

Radiofrequency ablation

Radiofrequency ablation is a minimally invasive procedure where the needle probe is first inserted into the center of the tumor. Metal prongs are then projected out from the needle’s hollow core and penetrate the tumor. Subsequently, high-energy radio waves are passed through the needle to its tip and prongs. This creates a small area of heat that kills the cancer cells in the liver (in a process called coagulative necrosis) and closes small blood vessels, which lowers the risk of bleeding. Bit by bit, the dead tumor cells are replaced by scar tissue that eventually shrinks.

This ablation technique is best suited for small liver tumors, especially those less than 3 cm in size and when there are no more than three tumors. If you have multiple lesions, you may need several procedures to get rid of all of them.

Microwave liver ablation

Microwave liver ablation works in a similar way to radiofrequency ablation, but instead of radio waves, microwaves are transmitted through the probe. This generates heat that burns the tumor and destroys the cancer cells. It can also make the tumor more sensitive to the effects of radiation and some anti-cancer drugs.

Liver tumors located near blood vessels can be more difficult to treat using radiofrequency ablation or microwave ablation. This is because the blood flowing through the vessels cools the tissue, preventing these techniques from reaching optimal temperatures. As such, the heat emitted won’t be as effective in destroying the cancer cells. This is referred to as the heat-sink effect, which may prevent complete tumor necrosis.

Cryotherapy

Cryotherapy (or cryoablation) uses extremely cold temperatures to destroy cancerous tissue. Using an imaging technique as guidance, your doctor inserts a thin, wand-like needle known as a cryoprobe through your skin and directly into the tumor. Argon or nitrogen gas is then pumped through a tube and into the cryoprobe, bringing the temperature of the tumor to extremely low levels. This freezes and destroys the tumor. Cryotherapy may work better for larger tumors.

Ethanol (alcohol) ablation

Also known as percutaneous ethanol injection (PEI), this form of chemical ablation involves the injection of ethanol (concentrated alcohol) directly into the liver tumor, creating a chemical burn that damages the cancer cells. PEI works best on tumors smaller than 2 cm. In some instances, especially for lesions larger than 2 cm, multiple treatments of alcohol ablation may be required or PEI may be used in combination with radiofrequency ablation or transarterial chemoembolization (TACE).

Histotripsy

Histotripsy involves the use of high-intensity sound waves to mechanically and selectively destroy cancer tissue in the liver. It is the first non-invasive, non-ionizing and non-thermal ablation technology guided by real-time imaging.

Other liver ablation techniques

Newer ablation therapies are currently being studied in clinical trials. One such technique, known as irreversible electroporation, is a procedure that doesn’t use heat or cold to kill cancer cells. Instead, it involves the use of electrical pulses or high voltage that is passed through an electrode to open the “pores” of the cell, which causes the cancer cells’ death. It can be very helpful for liver tumors located in difficult areas to treat, such as those close to blood vessels.

Ablation therapy is typically an outpatient procedure. While the time taken for the procedure depends on the specific technique used, the tumor’s size and other factors, it usually lasts one to three hours in total. It can be performed during open or laparoscopic surgery, or by inserting the needle through the skin (percutaneously).

This form of treatment can be done under general anesthesia (where you are in a deep sleep so you do not feel any pain) or with conscious sedation (where you are awake, but sleepy and should not experience any pain). If general anesthesia is needed, you might have a night’s stay in the hospital.

The area of your skin through which the needle probe is inserted is numbed with a local anesthetic. At the end, your radiologist removes the needle probe and applies pressure to stop any bleeding. The opening in the skin is then covered with a dressing.

Recovery afterwards can take about a week. Possible side effects and complications include:

• Abdominal discomfort or pain
• Infection in the liver
• Flu-like symptoms such as fever, body aches and feeling sick (collectively known as post-ablation syndrome)
• Collection of pus in the region where the tumor was removed (known as a liver abscess)
• Bleeding
• Damage to nearby organs (e.g., diaphragm, bile ducts), which may need surgical correction

You will be provided with painkillers and anti-sickness medication to manage some of the side effects. If these problems grow more severe or if they do not resolve, do inform your doctor(s).

Please be assured that follow-up imaging tests, such as CT or magnetic resonance imaging (MRI) scans, will be performed to examine how well the treatment has worked and to monitor the treated tissues over time.