What is thermal ablation?

Thermal ablation is used to treat different types of cancer. It uses extreme temperatures (thermal) to destroy (ablate) cancer cells.

There are different types of thermal ablation. This information is about the most common types, which are:

  • Radiofrequency ablation (RFA)

    For RFA, the doctor uses a needle called an electrode. They put the electrode into the tumour and apply an electrical current (radiofrequency) to it. This causes heat, which destroys the cancer cells. The treated area slowly shrinks and becomes scar tissue.

  • Microwave ablation (MWA)

    For MWA, the doctor sends microwave energy through a needle and into the tumour. This causes heat, which destroys the cancer cells. The treated area slowly shrinks and becomes scar tissue.

  • Cryotherapy

    In cryotherapy, the electrode destroys the cancer cells by freezing them. The doctor puts a needle called an electrode into the tumour to freeze and destroy the cancer cells.

Other thermal ablation treatments include:

  • laser therapy
  • high-intensity focused ultrasound (HIFU)

These treatments are done in a different way. We may have more information about them on our pages for the type of cancer you have. Your doctor can also tell you more.

You can have thermal ablation more than once. It may take more than one treatment to destroy as many cancer cells as possible. If the tumour starts to grow again, you may have more thermal ablation treatment.

How thermal ablation is given

You can have thermal ablation in different ways. It depends on the type of tumour and where it is in the body. Your doctor or specialist nurse will explain how the treatment will be given.

You may have thermal ablation in one of the following ways:

  • Percutaneous ablation

    This is the most common method and it does not use surgery. The doctor puts the electrode into the tumour through the skin. They use images from an ultrasound, CT scan or MRI scan to guide them.

  • Laparoscopic ablation

    This involves surgery. The surgeon makes several small cuts through the skin and muscle. They put a mini-telescope (laparoscope) through one of the cuts. This helps them guide the electrode into the tumours.

  • Open surgery

    The surgeon does the ablation at the same time as an operation to remove other tumours.

Before having thermal ablation

Your doctor or specialist nurse will ask you not to eat for several hours before your treatment. If you take any medicines, they will usually ask you to take them as normal. Tell your doctor if you take medicines for:

  • thinning your blood, such as aspirin or warfarin
  • diabetes.

Your doctor will give you instructions about when to stop taking these, or if you should take a different dose.

Before the treatment, you see a doctor who will explain the procedure. This is a good time to ask questions if you are unsure about anything. A doctor or nurse will ask you to sign a form to say that you agree (consent) to the treatment.

A nurse will give you a hospital gown to change into. A doctor or nurse will then place a fine tube (cannula) into a vein in your arm or on the back of your hand. They may also take blood samples to check your general health.

Having thermal ablation

You have thermal ablation in the hospital scanning department, or in an operating theatre. A doctor who specialises in x-rays and scans (radiologist) gives you the treatment.

Treatment takes around 1 to 3 hours. This depends on the size and number of tumours being treated. It is possible to have treatment as an outpatient, but you will usually need to stay overnight in hospital. If you are having the treatment as an outpatient, you will need to arrange for someone to take you home.

You may have thermal ablation under a general anaesthetic. Or you may have a local anaesthetic to numb the area, and a sedative to make you sleepy.

After you have had the anaesthetic, you will have an ultrasound or CT scan. These scans help the doctor guide the electrode into the right position. They also help the doctor monitor what is happening during your treatment.

When the electrode is in the right position, the tip is heated for RFA and MWA, or cooled for cryotherapy.

An area of healthy tissue around the tumour is usually also treated. This is because it may contain cancer cells.

If you have a larger tumour or more than one tumour, the doctor may reposition the electrode and repeat the treatment. Or they may use more than one electrode.

What does thermal ablation do?

Thermal ablation can be used with the aim of:

  • curing a cancer
  • reducing the size of a tumour
  • relieving pain (palliative treatment).

You can have it on its own, or with other cancer treatments.

Thermal ablation may be used instead of surgery, if surgery would be difficult. Or it can be used if you are not well enough to have a big operation.

You may have thermal ablation if the tumour:

  • can be reached by an electrode
  • can be seen on a CT scan or ultrasound scan
  • is not next to other organs where there is a risk of injury.

Thermal ablation is mainly used to treat:

We have more information about treatment for your type of cancer.

Possible side effects of thermal ablation

Side effects do not usually last more than a few days. You may have one or more of these side effects.

Pain or discomfort

You will probably have some pain or discomfort in the area that was treated. Your doctor will prescribe painkillers for you to take regularly for a few days. Sometimes people have pain in their shoulder after treatment to the liver or lung. Others may have pain in their hip after treatment to the kidney. For most people, any pain or discomfort lasts for less than a week. If your pain is not controlled, or if it lasts for longer than a week, tell your doctor.

We have more information about managing pain, which you might find helpful.

Feeling unwell with a raised temperature

For the first few days after treatment you may have a slightly raised temperature (between 37°C and 37.5°C). And you may feel tired and unwell.

If you had treatment for a larger tumour, or for more than one tumour, you are more likely to have these side effects. This is a normal reaction and is caused by your body clearing away the cells that have been destroyed by the treatment.

Try to drink plenty of fluids and rest for a few days. You should be able to get back to your usual activities after about a week.

If your temperature goes above 37.5°C or does not return to normal (36°C to 37°C) after a few days, you might have an infection. Contact your doctor straight away.

Blood in your urine (pee)

You may have some blood in your urine after thermal ablation to the kidney. This should only last a few days.

Possible complications of thermal ablation

The risk of complications is low. These are the main complications that can occur.

Bleeding from the area being treated

There is usually very little bleeding during the treatment. Sometimes people have more serious bleeding during or straight after the procedure. The nurses and doctors will check for bleeding during, and for a few hours after, treatment. This means, if it happens, it can be treated straight away.


You might get an infection in the area that was treated. You may be given antibiotics to reduce the risk of this happening. Symptoms of an infection include:

  • redness or discharge
  • pain in the area that was treated, which does not go away after a few days
  • a raised temperature (fever)
  • feeling generally unwell.

Contact your cancer doctor or specialist nurse for advice if you think you have an infection.

Collapsed lung (pneumothorax)

Part of the lung, or the whole lung, may collapse. This is most likely to happen when a tumour in the lung is treated. It can also happen when cancer in the liver or upper kidney is treated, but this is rare.

A collapsed lung can cause breathlessness. This may sound frightening, but it is not usually serious. The lung gets better on its own over a few days. Most people do not need any treatment other than painkillers. Some people need to have a tube placed into their chest for a short time, to help the lung expand back to full size.

Damage to the organs close to the area being treated

This is rare. Doctors use scans to guide the electrode into place during thermal ablation. But some people are at greater risk because of the size or location of the tumours.

Thermal ablation to the:

  • liver can sometimes damage nearby bile ducts. This causes yellowing of the skin (jaundice).
  • kidney can sometimes damage the ureter. This is the tube that carries urine from the kidney to the bladder. Further treatment may be needed to repair any damage.
  • liver or kidney can, rarely cause damage to the bowel.

About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.