Selective Internal Radiation Therapy (SIRT), also known as radioembolisation

What is Selective internal radiation therapy (SIRT)?

Selective internal radiation therapy (SIRT) is a way of giving radiotherapy treatment for cancer in the liver that can’t be removed with surgery. It’s a type of internal radiotherapy, and is sometimes called radioembolisation.

Millions of tiny radioactive resin ‘beads’ or spheres  are injected through a small tube (catheter) directly into the vessel(s) that feed the liver tumour(s). These tiny spheres, which contain a radioactive substance called yttrrium-90, are passed down a thin tube into the hepatic artery (one of two arteries that supply the liver with blood). The spheres are made from either glass (TheraSphere) or resin (Sir-Spheres). The spheres form clusters in the small blood vessels around the tumour and release radiation to destroy the cancer cells.

Who is the treatment available for?

The National Institute for Health and Care Excellence (NICE) has approved SIRT as an option for some people with hepatocellular carcinoma (HCC) in England and Wales. It is expected that patients from Northern Ireland will also be able to access treatment. It recommends the use of SIR-Spheres (made by SIRTEX) and TheraSphere (made by Boston Scientific) for treating advanced liver cancer that can’t be surgically removed and when a procedure to cut off the blood supply to the tumour (transarterial therapy) isn’t appropriate. The guidance specifies that SIR-Spheres and TheraSphere should only be considered for people with Child-Pugh grade A liver impairment. The Child-Pugh grading system classifies how well the liver is working to establish the most suitable type of treatment. Child-Pugh grade A means the liver is working normally.

SIRT has also been approved for people with advanced bowel cancer that has spread to liver.

If you think SIRT may be a helpful treatment for you, speak to your clinician.

Is it available in Scotland?

SIRT is not currently available on the NHS in Scotland. The British Liver Trust attended meetings and made several submissions to NICE on behalf of patients. The Trust is delighted that these views have now been listened to and this new treatment can now be made available on the NHS in England Wales. We will do the same for patients in Scotland when the Scottish Medicine Consortium considers the treatment.

How does the treatment work?

SIRT is usually carried out by a specialist doctor called an interventional radiologist. Usually two sessions of about 60 – 90 minutes are needed, each under conscious sedation.

Before you have SIRT, you’ll have something called a planning or work-up angiogram, which looks at the blood supply to the liver. This is to make sure the SIRT spheres, known as microspheres, can’t travel to other areas of the body and damage healthy tissue. The interventional radiologist will insert a tube through an artery in the groin (femoral) or wrist (radial). Dye is then injected through a catheter and into the liver to show up blood vessels that lead to other parts of the body, which may need to be blocked. The procedure is performed under local anaesthetic to ensure you’re comfortable and conscious sedation may be offered.

After the angiogram, the doctor will inject a radioactive ‘tracer’ called technetium 99m-MAA into the catheter. The tracer is similar in size to the SIRT microspheres but is a pure gamma emitter. You then have a scan that picks up the distribution of the radioactive tracer. This shows where the spheres will go when you have the treatment and helps your doctor to work out if it’s safe to go ahead. Another work-up may be necessary if this scan demonstrates unexpected uptake, which is correctable.

You have SIRT a week or two after the planning angiogram. The treatment is again given via a catheter. When the catheter is in the right place, the doctor slowly injects the microspheres into your liver. It takes about an hour, and afterwards, if groin (femoral) access is performed, you’ll need to lie flat for a few hours so the wound can start to clot and heal. If wrist (radial) access is used, you will be able to sit up immediately following the procedure.

Will I have to stay in hospital overnight?

Planning and treatment procedures may be performed as day cases but most centres require people to stay in hospital overnight and you’ll be give painkillers and anti-sickness medicines if you need them. Occasionally, the SIRT treatment is delivered in two stages with a 4 to 6 week interval between each treatment, where the right and left lobes of the liver are treated separately.

What are the side effects?

Generally the side effects of SIRT are mild. They include:

  • a raised temperature
  • chills
  • feeling sick
  • diarrhoea
  • stomach ache
  • a feeling of pressure in the abdomen
  • mild fatigue, although you should still be able to do everyday activities.

These side effects usually only last a few days. Contact your doctor or the hospital if you develop a high temperature (above 38C) as you might have an infection or if you experience severe side effects or if they last more than three days.

Will I lose my hair?

Hair loss (alopecia) has never been reported following treatment with the microspheres. The microspheres do not worsen hair loss due to chemotherapy.

Is there a risk from the radiation?

The range of radiation from the microspheres is very small. However, you should avoid close contact (being within arm’s length) with young children and pregnant women for the first 10 days after treatment. Your doctor might also advise you not to share a bed for the first four days. All radiation will have left the body within two weeks - the microspheres stay in the liver permanently but are harmless.

Will I have to stop my other therapy treatments to receive SIRT?

Generally, most patients’ therapy is stopped before receiving SIRT. However, your clinician will determine if your therapy needs to be stopped during the treatment period.

What happens after treatment?

Sometimes a scan is done after the procedure to confirm the placement of the microspheres. You will be monitored for a few hours and discharged within the next 1–3 days. As with any surgical procedure, on the day of discharge, limit your activities. You should not do any physical exercise or heavy lifting for the next 3 days, but generally you may resume all other daily activities 24 hours after treatment.

Your specialist will then follow-up closely after treatment. How they do this varies slightly between hospitals - your doctor and specialist nurse will talk to you about how often you will have check-ups and scans. SIRT releases radiation that may affect liver tissue. As a result, your doctor will routinely test your blood to monitor liver function and identify any potential risks that might occur.

Hear from a patient about their firsthand experience of SIRT.