Stereotactic ablative body radiotherapy (SABR) for metastatic cancer

What is SABR?

SABR is a very effective treatment technique, giving a high dose of radiotherapy to the tumour and reduced radiation dose to surrounding normal areas. It is a very precise treatment which uses advanced imaging techniques to guide the radiotherapy. It uses higher doses of radiotherapy per treatment compared to standard radiotherapy.

This means that the treatment can be completed in fewer visits to hospital. Radiation also damages normal cells in or around the area being treated which causes side effects, but these will usually recover and heal after treatment.

How is SABR given for metastatic cancer?

SABR for metastatic cancer is given in three, five or eight sessions, depending on the location of your cancer. Your oncologist will tell you how many treatments you will be having.

SABR is given on weekdays with at least 40 hours between sessions. It is a highly effective curative treatment for cancers that have spread to only a limited number of sites in the body (oligometastatic).

SABR can be offered to reduce the pain or other symptoms from the site of treatment, to delay the need for or prolong the effectiveness of chemotherapy or hormone therapy and to prevent further spread of cancer.

Alternative treatments include: surgery, chemotherapy or hormone therapy, and
observation. Your doctor will discuss which (if any) of these treatments may also be suitable for you. Your doctor will also discuss the relative merits of these different approaches for you to consider and decide which is best for you.

You will need to attend the radiotherapy department as an outpatient, for a course of two to three treatments a week for one to three weeks.

Your radiotherapy planning appointment

Radiotherapy machines delivering SABR treatment must be able to accurately determine the position of the tumour being treated. This may be done using external scans, but in some cases may require insertion of small markers (fiducial markers) into or around the tumour. The insertion itself requires a small operation.

Prior to your radiotherapy treatment starting, you will need to attend the radiotherapy department for a CT planning scan.

Various techniques may be used to assist in keeping you comfortably in the right position for your treatment and to allow us to ensure that your internal anatomy is in the same place each day for treatment.

Which of these are required for you will be decided specifically for you based on exactly where is being treated following discussion with a group of experts and will be explained to you. The most used methods are listed below, and we may give you additional information leaflets relating to them.

Depending on the area to be treated they may arrange for you to have a specially made mask to help keep your neck still during your treatment. They will explain this to you if it is needed.

Your planning CT scan may have two parts. One will take a little longer and will involve us recording your breathing using a box placed on your chest at the same time as taking the scan.

This allows us to build a moving picture of your chest to see how things move as you breathe so that we can take this into consideration when we plan your treatment. The other part will be quicker and will not involve monitoring your breathing.

You may be required to fast before your planning scan and treatment. This will mean that you cannot eat for two hours and will be given a cup of water immediately prior to the procedure.

You may be asked to have a full bladder and empty bowels for your radiotherapy. We ask that you ensure you are drinking two to three litres of water a day from at least one week before your planning appointment.

Please follow the specific drinking schedule provided for you on the days of your appointments. You may also be given medications to assist in emptying your bowels.

Some patients may be required to have abdominal compression as part of their treatment. This is used to reduce the amount your organs move during your normal breathing. It is not painful and if suitable will need to be used every day when you have your treatment. It involves a piece of equipment being wrapped around your abdomen which gets inflated.

Sometimes you may be asked to hold your breath. Sometimes this is following a deep inhalation (DIBH) or at a natural exhalation (EEBH). This may be at just your planning appointment or at all your treatment appointments as well.

This allows us to get better quality CT images and stops your organs moving because of breathing while delivering treatment. It can also sometimes be used to move area of treatment away from other organs in your body.

Your radiotherapy treatment appointments

The actual radiotherapy treatment is like having an x-ray/scan. Each session takes
approximately 30 minutes to an hour in total, most of which is spent ensuring you are in the correct position, although the actual delivery of the radiation lasts only a few minutes.

Sometimes it can take longer if your internal organs are not in the correct position. On rare occasions we may not be able to proceed with your treatment if we cannot be confident that it is going to be as accurate as needed.

Short-term side effects

Some side effects are short term or “acute”. Short term side effects typically reach their peak about two to three weeks after you finish your treatment and take a further two to three weeks to reduce, however this will not be the case for all patients.

Potential side effects will depend on the area of the body being treated. Your doctor will discuss the relevant side effects for your treatment. Examples of possible short term side effects from SABR for metastatic cancer are listed below.

Skin issues

Your skin may become slightly discoloured over the treated area. We advise you not to soak in hot baths. Use a mild, non-perfumed soap and pat the area dry rather than rubbing it. Do not use talcum powder or any lotions and creams other than those advised by us. Cream is available from the radiotherapy review specialist if you need it and wearing loose, natural fibre clothing also helps.

Tiredness

Radiotherapy may make you tired. Gentle exercise can help with your recovery.

Sore throat

You may experience a sore throat if you are having your neck or upper chest treated.

Sickness

You may experience nausea and vomiting if you are having your abdomen, pelvis, or lower spine treated. This can happen just a few hours after treatment or at any time during the treatment course. You may develop discomfort in the area being treated. This is usually mild and relieved with simple pain killers.

Bowel habits

You may experience changes in bowel habits if you are having your abdomen, pelvis, or lower spinal treated. Drinking plenty of liquid will replace lost fluids if this happens.

Hair loss

You may notice that your body hair falls out in the treated area. This only happens in the area that has been treated and may grow back depending on the dose of radiotherapy.

Temporary increase in pain

You may experience a temporary increase in pain in the area being treated. This normally lasts less than two days and can be managed with your standard pain relief. You may experience some or all these side effects. Please always let the radiotherapy team know of anything worrying you, as we want to help you recover as soon as possible.

Long-term side effects

Some side effects are long term. These usually occur more than three months after
finishing your course of treatment but sometimes can start much later.

Bone fracture (break)

This may occur when bony areas are treated and can cause pain, the most common
example being a rib fracture when a lung metastasis is treated.

Liver and / or kidney damage

This may occur for treatments in the abdominal region. It can be assessed using blood
tests.

Bowel damage

This may lead to a blockage in the bowel (gut) requiring an operation.

Damage to nerves and spinal cord

This is relevant to treatments of, or close to, the spine. We will be careful and keep the dose to these areas as low as possible while delivering an effective treatment. Please let your doctor know if this happens – you may require additional tests and there may be treatments that can be offered to help.

After your treatment

Follow up from radiotherapy can vary depending on the treatment you have received. Sometimes you may be referred back to your surgeon for follow up and sometimes you will be followed up by your radiotherapy doctor.

Usually, you should expect an outpatient appointment to be arranged for four to six weeks after completing your treatment. This may sometimes be a telephone appointment. Outpatient appointments will then continue initially on a three to six monthly basis, or more frequently if required.

Support available at the Royal Free Hospital

We have several support services available for you to access. If you would like to know more about these, please read our leaflet titled: ‘A Patient’s Guide to Radiotherapy’ or ask a member of the radiotherapy team.