Selective internal radiation therapy (SIRT) is a way of giving radiotherapy treatment for cancer in the liver. This can be cancer that started in the liver or cancer that has spread to the liver from somewhere else.
What is selective internal radiation therapy (SIRT)?
SIRT is a way of using radiotherapy to control cancers in the liver that can’t be removed with surgery. It is a type of internal radiotherapy. It is sometimes called radioembolisation or trans arterial radioembolisation (TARE).
Your doctor puts tiny radioactive beads (called microspheres) into a blood vessel (artery) that takes blood into your liver. The beads get stuck in the small blood vessels in and around the cancer, and the radiation destroys the cancer cells.
As the radiation only travels a few millimetres from where the beads are trapped, it should cause little damage to the surrounding healthy tissue.
Who can have SIRT?
SIRT will be available on the NHS in England for bowel cancer that has spread to the liver (liver metastases) from April 2019. It is for some people with bowel cancer that has only spread to the liver and it can’t be removed with surgery, and chemotherapy is no longer working.
SIRT can be used for other types of cancers in the liver, such as cancer that started in the liver (primary liver cancer). But this isn’t available on the NHS at the moment.
For these other types of cancer, or if you live in other countries of the UK, your doctor might be able to submit a funding request to see if you can have SIRT on the NHS. Or you might be able to have it as part of a trial (if there is one available). Or you might be able to pay for it privately.
Doctors continue to research SIRT and collect information on how well it works for different types of cancers in the liver.
Tests before SIRT
Before you have SIRT, you have tests to check your liver and plan your treatment.
A CT scan shows where the tumours are in your liver and their size. So your doctor can check that SIRT is a suitable treatment. You might not need another CT scan if you have recently had one for something else.
You have blood tests to check:
- the number of different blood cells (a full blood count)
- how well your kidneys and liver are working
- there are no problems with your blood clotting
A planning angiogram
An angiogram looks at the blood supply to the liver, which varies from person to person. The doctor (called an interventional radiologist) blocks off tiny blood vessels that lead to other areas of the body like the stomach or lungs. This stops the SIRT beads from travelling to other areas of the body and damaging healthy tissue. The procedure usually takes 60 to 90 minutes but may take longer.
First you might have some sedation to help you relax. Then you have an injection of local anaesthetic to numb the area at the top of your leg (the groin) or your wrist. Your doctor makes a small cut and puts a thin tube (called a catheter) into a blood vessel called an artery.
Your doctor guides the catheter into your liver using x-rays. They then inject a dye to show up all the blood vessels. They can see the images on a screen. The dye might make you feel warm for a few seconds and you might feel as though you need to pass urine.
Your doctor can see if there are blood vessels that lead to other areas of the body and can block them with tiny coils. This doesn’t harm the areas that these small blood vessels go to.
Lung shunting scan
After the angiogram, your doctor injects a radioactive tracer into the catheter. The tracer is similar in size to the SIRT beads.
You then have a scan that picks up the radioactive tracer. This is called a lung shunting scan or SPECT CT. This takes about an hour. It shows where the beads will go when you have the treatment. This helps your doctor to work out if it is safe to go ahead with the treatment.
You need to lie flat for several hours after these tests if your doctor put the catheter into an artery in your groin. This helps the wound to heal. You can usually sit up straight away if they used an artery in your wrist.
You usually go home the following morning.
How you have SIRT
You have SIRT about 1 or 2 weeks after the planning angiogram.
First you have another angiogram as above. You have sedation to help you relax and painkillers to keep you comfortable.
When the catheter is in the right place, your doctor slowly injects the radioactive beads into your liver. The whole process takes about an hour.
When your doctor removes the catheter they put a dressing over the small wound. You need to lie flat for around 6 hours if the catheter went into an artery in your groin. Most people need to stay in hospital overnight. Your nurse will give you painkillers and anti sickness medicines if you need them.
You have a scan the day after treatment to check the position of the radioactive beads.
Side effects of SIRT
For most people the side effects of SIRT are mild. They include:
- a raised temperature
- feeling sick
- stomach ache
- a feeling of pressure in your tummy (abdomen)
These side effects usually only last a few days. Your nurse will give you medicines to help. Contact your doctor or the hospital if you develop a high temperature (above 38C) as you might have an infection.
Tiredness is a common side effect and can last up to 6 weeks. This is normally mild, so you can still do normal everyday activities. Severe tiredness is quite rare. Talk to your specialist nurse if you are worried.
Irritation to the gut
Rarely, a small number of the microspheres can travel to the digestive system (gut). This can cause:
- pain in your abdomen
- feeling or being sick
- a stomach ulcer
- inflammation of the pancreas (pancreatitis)
To prevent irritation to the stomach, your doctor will give you anti ulcer medicines for around 4 to 8 weeks after treatment.
Inflammation of the gallbladder
This is called cholecystitis. Symptoms include:
- feeling or being sick
It may get better without treatment, but in rare cases you may need surgery to remove the gallbladder.
If the radioactive beads go to the lungs they can cause inflammation. This is very rare. It may cause a cough and shortness of breath. Your doctor might give you steroids to help.
Inflammation of the liver
This can affect how well your liver works, and may happen weeks after the treatment. You will have regular blood tests (liver function tests) to check this.
Your liver function might get better by itself after a few weeks. Or you may need steroids or other medicines. Damage to the liver can be life threatening, but this is extremely rare.
Radiation safety after SIRT treatment
For the first 24 hours after treatment you should make sure you thoroughly wash your hands after going to the toilet.
The range of radiation from the beads is very small. But as a precaution, you might be told to avoid close contact with young children and pregnant women for the first week after treatment. Your doctor might also advise you not to share a bed with your partner for the first night or two.
The advice about this can vary slightly between hospitals, so be sure to follow the instructions from your own doctor or specialist nurse.
Most of the radiation from the beads has gone within 2 weeks. The beads stay in the liver permanently but they are harmless.
Your specialist will follow you up closely after treatment. How they do this varies slightly between hospitals.
You will have regular blood tests to check how well your liver is working. You might have a CT scan around 2 or 3 months after treatment.
Your doctor and specialist nurse will talk to you about how often you will have check ups and scans.