Selective Internal Radiation Therapy (SIRT)
What is Selective Internal Radiation Therapy?
Selective Internal Radiation Therapy or SIRT delivers radiation therapy directly to the tumour. It uses tiny radioactive beads that are injected into your bloodstream. The tiny radioactive beads are known as SIR-Spheres®, and are less than the width of a human hair. They contain the radioactive element yttrium-90 (Y-90), which delivers radiation over a very short distance inside your body. The SIR-Spheres® are injected directly into the blood vessels feeding the tumour via a plastic tube inserted into your groin. The SIRSpheres® lodge in the small blood vessels of the tumour.
- Because the radiation has a short range, it kills tumour cells but not the surrounding healthy tissue. SIRT is an approved treatment for liver tumours that cannot be removed by surgery. These could either be cancers that started in the liver (primary liver cancer) or that have spread to the liver from another part of the body (secondary liver cancer or metastases).
- The procedure consists of two stages carried out one or two weeks apart. Both stages involve an angiogram followed by a radioactive injection and then a gamma camera scan. The procedure is explained in full below.
Why is this treatment being considered for me?
You may have already had other treatments, including chemotherapy or surgery. These treatments may no longer be effective on your cancer. A team of specialist doctors have decided to offer you this treatment as they feel it is the best option for you.
What is involved?
Before the therapy, you will have a CT scan that the doctors will use to plan the treatment. The treatment consists of two stages. Both stages will be carried out by a Consultant Interventional Radiologist. This is a senior doctor who specialises in image-guided treatments.
Stage 1: Assessment
The doctor will examine the blood supply to your liver and block off any blood vessels that do not directly feed the tumour. This is called embolisation. Embolisation helps to maximise the effects of the Treatment. It also prevents the SIR-Spheres® from travelling to other organs outside the liver, which reduces the risk of side-effects. A radioactive tracer is then injected that mimics the treatment. A gamma camera scan then checks the distribution of this tracer in the body. This acts as a guide for where the SIR-Spheres® will be delivered in your body.
The details of this stage are:
The procedure is performed with local anaesthetic in the groin. You will be awake for the whole procedure, and will be able to talk to the doctor and nurse looking after you.
- Painkillers and sedatives are not normally required, but we will place a needle in your arm in case we need to give you these injections.
- You will lie on a couch in an angiography room. This is similar to an operating theatre but also contains special x-ray equipment used to look at your blood vessels.
- A nurse will monitor your breathing and heart beat during the procedure. Everything must be kept as sterile as possible, so the doctor and some of his team will be wearing surgical gowns and gloves.
- The doctor will gain access to your blood vessels through a catheter inserted into an artery in your groin.
- The doctor will use x-ray equipment and small amounts of x-ray dye to guide the catheter. He will position it in several small blood vessels around the liver. Several pictures of the blood supply to your liver and other organs will be taken. This is called an angiogram. The doctor will insert tiny coils of wire through the catheter to block off some of your blood vessels. This reduces the risk of the Sir-Spheres® travelling to areas outside the liver.
- The angiogram and embolisation may take several hours.
- A small amount of radioactive tracer will then be injected. The tracer is similar to the SIR-Spheres®, but contains a radioactive element called Technetium-99m. This can be easily detected by a type of scanner called a gamma camera.
- You will be moved onto a trolley and taken by a porter to the Nuclear Medicine Department for a gamma camera scan. A nurse will accompany you and continue to monitor you during the scan. For the gamma camera scan, you will lie on a couch and a radiographer will position two large cameras above and below you. These will scan slowly over your abdomen taking a picture of the radioactive tracer. The cameras will then rotate slowly around you as a 3D picture is also taken. This scan lasts for about an hour.
- The gamma camera scan will show how the Sir-Spheres® will be distributed in your body. This provides a guide to your doctors that it is safe to proceed with the treatment. You will be moved back onto the trolley and taken to the ward. You will need to remain lying flat for several hours to allow the puncture wound in your groin to heal.
- You will be able to go home at the end of the day, or early the next morning.
Stage 2: SIR-Spheres® Treatment
This stage is carried out one to two weeks later. The procedure is very similar to Stage 1. You will have another angiogram to check that no new blood vessels need embolising. The doctor will also position the catheter for injection of the SIR-Spheres® into your liver. The SIR-Spheres® have to be injected very slowly, and sometimes into different vessels separately. This procedure takes time, but it is normally shorter than the previous angiogram. Afterwards, you will be transferred to the ward where you will stay overnight. On the following day, you will have another gamma camera scan to confirm the placement of the SIR-Spheres®. This scan will again last about an hour. You will be discharged from the ward and will be able to go home. You will be given the contact details of the Clinical Nurse Specialist who will organise your follow-up appointments and CT scan.
What are the benefits?
The SIRT procedure allows us to target and kill liver tumours whilst minimising damage to the healthy liver. It can be used on its own, or together with chemotherapy to stop liver tumours growing, or to cause them to shrink. Evidence is still being collected on the success rates of the therapy and how it fits best with other treatments. However, the information that has been published so far is encouraging. There is evidence for an improvement in quality of life and an increase in life expectancy. In a small number of patients, SIRT can shrink the liver tumours enough to make it possible to surgically remove the tumours at a later date.
What are the risks?
As with all cancer treatments, there are some potential complications of the SIRT procedure. These complications are all very rare, but you need to be aware of them.
They are detailed below:
- Radiation damage to the liver. Despite the SIR-Spheres® concentrating in the tumours, there will always be some effect of the radiation to healthy liver. If this occurs, it is usually short-lived. However, in rare cases it can be enough to cause significant liver damage or failure. This is more likely if you already have other liver disease, such as cirrhosis. Radiation damage to other organs. The first stage of the treatment is designed to ensure the SIR-Spheres® are delivered only to the tumour. However, there is a small chance that some of the SIRSpheres may end up in blood vessels supplying other organs. These organs could include the lungs, stomach or pancreas. The radiation can damage these organs, causing inflammation (pneumonitis, gastritis, and pancreatitis). These may require further medical treatment.
Damage to blood vessels; some chemotherapy can make blood vessels very fragile and sensitive to damage during angiography. This may sometimes make it impossible to complete the SIRT treatment.
Preparation for the treatment
You will be asked not to eat for four hours prior to each stage of the treatment. You may drink water until two hours before the procedure. You will be able to eat and drink normally after the treatment.
What happens after the treatment?
Because this is a radioactive treatment, there are some simple precautions that you must follow after the second stage of the treatment. These include thoroughly washing your hands after using the toilet and cleaning up any spills of body fluids promptly and disposing of them down the toilet. A medical physicist will explain the precautions at the end of your treatment. You will be given a yellow card with the details to take home with you. After you are discharged, you will have regular blood tests and scans to monitor the success of the therapy. Your doctor will see you in a follow-up clinic two weeks after the treatment, where you will have blood tests to monitor your liver function. You will have a CT scan of your liver eight weeks after the treatment. This is to monitor your response to the therapy. The doctor will discuss this with you in a clinic appointment one week after your CT scan.
What are the alternatives?
There are several alternative techniques that can be used to treat liver tumours. These include surgery, chemotherapy, chemo-embolisation and local ablation (such as radio-frequency ablation). The decision about which of these treatments is most appropriate for you has been taken by a team of specialist doctors. They have taken your personal circumstances into account. Your doctors will be happy to explain how SIRT fits into the overall treatment strategy for you.
For Further Information
Patient Advice and Liaison Service (PALS) at the RSCH
Telephone: 01483 402757