Ablation and Embolization for Colorectal Cancer

When colorectal cancer has spread and there are a few small tumors the liver or lung, these metastases can sometimes be removed by surgery or destroyed by other techniques, such as ablation or embolization.

When all of the primary cancer in the colon or rectum can be removed with surgery, these techniques might be used to destroy small spots of cancer if it has spread.

Ablation and embolization might also be good options for people whose metastatic tumors come back after surgery, whose cancer can’t be cured with surgery, or who can’t have surgery for other reasons. This might help a person live longer. It can also help treat problems the tumor is causing, like pain.

In most cases, patients don't need to stay in the hospital for these treatments.


Ablation refers to treatments that destroy small (less than 4 cm across) tumors without removing them. The use of radiofrequency ablation to treat cancer that has spread to the liver is best understood. But there are many different ablation techniques, and ablation can be used to treat tumors in other places, too.

Radiofrequency ablation

Radiofrequency ablation (RFA) uses high-energy radio waves to kill tumors. A CT scan or ultrasound is used to guide a thin, needle-like probe through the skin and into the tumor. An electric current is then sent to the tip of the probe, releasing high-frequency radio waves that heat the tumor and destroy the cancer cells.

Microwave ablation (MWA)

This newer ablation method is used to treat cancer that has spread to the liver. Imaging tests are used to guide a needle-like probe into the tumor. Electromagnetic microwaves are then sent through it to create high temperatures that kill tumors quickly. This treatment has been used to treat larger tumors (up to 6 cm across).

Ethanol (alcohol) ablation

In this technique, also known as percutaneous ethanol injection (PEI), concentrated alcohol is put right into the tumor to kill cancer cells. This is usually done through the skin using a needle, which is guided by ultrasound or CT scans.

Cryosurgery (cryotherapy or cryoablation)

Cryosurgery destroys the tumor by freezing it with a thin metal probe. The probe is guided through the skin and into the tumor using ultrasound. Then very cold gasses are passed through the end of the probe to freeze the tumor, killing the cancer cells. This method can treat larger tumors than the other ablation techniques, but it sometimes general anesthesia is needed (drugs are used to put the patient into a deep sleep). Treatment can be repeated as needed to kill all the cancer cells.

Side effects of ablation therapy

Possible side effects after ablation therapy include:

  • Abdominal (belly) pain
  • Infection
  • Bleeding into the chest cavity or abdomen

Serious complications are rare, but they are possible.


During an embolization procedure, substances are injected into blood vessels to try to block or reduce the blood flow to cancer cells in the liver. This allows doctors to treat the metastatic tumors, while limiting the effects of treatment on the healthy parts of the liver, as well as the rest of the body.

The liver is unusual in that it has 2 blood supplies. Most normal liver cells get blood from branches of the portal vein, but cancer cells in the liver usually get their blood supply from branches of the hepatic artery. Blocking the branch of the hepatic artery that's feeding the tumor helps kill cancer cells, but it leaves most of the healthy liver cells unharmed.

Embolization can be used for tumors that are too big to be treated with ablation – usually larger than 5 cm (about 2 inches) across. It can also be used along with ablation. Embolization does reduce some of the blood supply to the normal liver tissue, so it may not be a good option for patients with liver damage from diseases like hepatitis or cirrhosis.

There are 3 main types of embolization procedures used to treat colorectal cancer that has spread (metastasized) to the liver:

  • Arterial embolization is also called trans-arterial embolization or TAE. In this procedure a catheter (a thin, flexible tube) is put into an artery through a small cut in the inner thigh and threaded up into the hepatic artery in the liver. A dye is usually injected into the blood at this time to help the doctor monitor the path of the catheter using x-ray pictures. Once the catheter is in the right place, tiny particles are injected into the artery to plug it up.
  • Chemoembolization (also called trans-arterial chemoembolization or TACE) combines embolization with chemotherapy. Multiple treatments may be given over 4 to 6 weeks. Most often, this is done by using tiny beads that give off a chemotherapy drug for the embolization. TACE can also be done by giving chemotherapy through a catheter that's put right into the artery that feeds the tumor, then plugging up the artery. The catheter is threaded up into the hepatic artery in the liver through a small cut in the inner thigh.
  • Radioembolization is a combination of embolization and radiation therapy. In the United States, it's done by injecting tiny beads (called microspheres) coated with radioactive yttrium-90 into the hepatic artery. The beads lodge in the blood vessels near the tumor. There, they give off small amounts of radiation for several days. The radiation travels a very short distance, so its effects are limited mainly to the tumor.

Side effects of embolization

Possible side effects after embolization include:

  • Belly (abdominal) pain
  • Fever
  • Nausea
  • Infection in the liver
  • Gallbladder inflammation
  • Blood clots in the main blood vessels of the liver

Because healthy liver tissue can be affected, there is a risk that liver function will get worse after embolization. This risk is higher if a large branch of the hepatic artery is used. Serious complications don’t happen often, but they are possible.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

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Last Medical Review: February 21, 2018 Last Revised: February 21, 2018

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