HIFU Clinical Trial Patient Information

Introduction to HIFU

This information sheet is intended to provide patients with sufficient information to enable them to make an informed decision regarding their participation in our clinical trials and their treatment with High Intensity Focused Ultrasound, or ‘HIFU’. Ask us if there is anything that is not clear or if you would like more information.

What is HIFU?

A new technique, involving high energy focused sound waves (focused ultrasound), allows us to destroy a precise volume of tissue within a tumour without harming surrounding structures. The full name of the device we use is the HAIFU™ JC-Focused Ultrasound Therapy System. It uses a high-energy, focused, ultrasound beam to heat and destroy, a very precise volume of tissue at its focus, and can be used to treat a large number of different tumours. Equipment of the type being used in Oxford has been used to treat upwards of 8000 patients worldwide. It is one of the first machines of its kind to be used clinically. Previous studies, using a similar research device at the Royal Marsden Hospital for the Institute of Cancer Research, UK, have shown that focused ultrasound is safe and has minimal or no side effects, and offers advantages over existing treatments.

In the trials the HIFU treatment aims to destroy either the whole of, or part of, the tumour. We would treat the patient under a general anaesthetic; this treatment would be in addition to any other medical treatment being received. Afterwards we would look at the tumour using magnetic resonance (MR) scans to check the success of the treatment.

What are the intended benefits of treatment?

In this treatment we hope to destroy the whole, or the part of the tumour that we are treating. If the tumour is small and localised to the target area, the intention of treatment will be curative. If the tumour is very extensive, or in a difficult anatomical region, it may only be possible to reduce the bulk of the tumour. In this case, the intention of treatment will be palliative, and the goals will be to increase survival and to improve quality of life. It is important that patients discuss their individual case with their doctor prior to treatment.

There is some evidence to suggest that HIFU treatment itself stimulates the immune system and reduces the chance of a further tumour developing. In some treated patients, tumours that were not directly targeted have been seen to become smaller, and even disappear. There is also evidence from Europe, where HIFU is being used to treat prostate cancer, of a similar immune response. This type of response is not yet proven, and it is too early to say definitively whether it really happens.

What are the side effects of treatment?

There is no evidence of side effects of diagnostic ultrasound. Clinical trials with focused ultrasound in Oxford have shown that there may be occasional damage to the skin. On the occasions that the skin has been affected, the effects were mild, the equivalent of sunburn, in 88% of cases. Improvements to the way that treatment sessions are now planned enables us to avoid such problems in the majority of cases. If the skin is being affected, it is possible to see this on ultrasound images at the time of treatment; in these instances we can then alter the direction of the ultrasound beam, or the treatment parameters.

The first patients to be treated with HIFU were treated without anaesthetic, and they often reported pain at the time of treatment. To avoid this, patients are now all treated under anaesthetic. 80% of patients feel some discomfort after the treatment, but in the majority it has been mild, and rarely lasted more than a few hours. It is usually easily controlled with standard pain relief tablets.

There is a very small risk of an infection in the area that has been treated, but this has only been seen in less than 1% of the first 1400 patients treated with the device. In order to minimise this risk, the patient would be given a 5-day course of antibiotics. All antibiotics can cause side effects such as nausea, diarrhoea and allergic reactions. There have been no treatment-related infections seen during the clinical study in Oxford.

There is also a risk of damaging normal tissue, such as the bowel - if this falls within the focal region of the ultrasound treatment. Simple and precise planning and targeting allow us to minimise this risk.

There is no evidence that HIFU can lead to the spread of a tumour.

No other direct complications of the treatment have been recognised, but the patient is strongly urged to mention any symptoms experienced to their doctor.

In addition to the side effects listed above, the need for a general anaesthetic involves risks of which are discussed below. These will also be explained to the patient by the anaesthetist before the procedure.

There are risks associated with undergoing any anaesthetic procedure. The known risk of death under anaesthesia in the UK is 1 in 150,000 anaesthetics. To put this in perspective, if we anaesthetised a volunteer every day for 400 years there would be one death.

Full safety equipment would be available at all times during the treatment. The anaesthetic would be administered by a fully trained anaesthetist and anaesthetic nurse. Their only responsibility would be to take care of the patient.

It is important to fast before the HIFU procedure as instructed. Any food or drink in the stomach when the anaesthetic drugs are administered might be regurgitated while anaesthetised or when being wakened. It is possible that the regurgitated substances could enter the airway preventing breathing. Such substances could also be inhaled into the lungs, which could cause pneumonia or infection.

Some post-anaesthetic nausea or vomiting may also be experienced - but the risk is less than 10%. We could give treatment for this if required. Most subjects will have a minor sore throat for 24 hours, and a dry cough for an hour or two. Minor bruises from drip-tubes in the back of the hand or arm are inevitable. There may be some discomfort on initial injection of one of the anaesthetic agents.

It is possible that the IV catheter may be improperly placed or may move, causing drugs to be infused under the skin. As with any puncture site, there is chance of infection if it is not kept clean.