UPDATE - Issue 20 - Winter 2004
High Intensity Focused Ultrasound
- a new treatment for prostate cancer
Localised prostate cancer can be cured by surgery or by radiotherapy. Both these treatments, however, may produce side effects that can negatively affect quality of life. Now, there is a new treatment being evaluated for use in the UK - High Intensity Focused Ultrasound (HIFU) - which, if the trials are successful, may prove an attractive option for patients.
The potential benefits of HIFU include a local rather than a general anaesthetic, and the possibility of returning home within a day of treatment. Incontinence rates are reputedly very low. Furthermore, because the surgeon can see the neurovascular bundles (which carry the nerves responsible for erectile function), it is claimed that the treatment can avoid these, resulting in fewer patients suffering from erectile dysfunction than with alternative treatments (figures of 20% rather than 60% have been reported). Damage to the rectal wall (a common side effect of radiotherapy) is also said to be less likely for patients treated with HIFU. And unlike radio-therapy, HIFU treatment can be repeated if necessary at a later date.
However, it is not yet certain whether complete tumour eradication can be achieved, and research is also required to ascertain the best approach to use for optimum results. It appears from trials in other countries that a "gentle" approach tends to produce the fewest side effects, but may not be as successful in eradicating the cancer, whereas a more aggressive approach may be more successful as a treatment but produce more significant side effects.
HIFU is a non-invasive technique which uses intersecting precision focused ultrasound waves. These raise the temperature of the tissue at the focal point to more than 80oC in 2-3 seconds, killing the targeted cancerous tissue.
Our first illustration shows the positioning of the HIFU probe in the rectum. This provides an ultrasound image and then treatment to the target area in a progression of overlapping ellipses. To protect the rectal wall the probe itself is cooled. The second illustration shows treatment in progress. Red areas have been treated; the orange one is currently being treated; green illustrates the planned paths for completion of treatment.
Three early trials are currently under way in the UK. Mr Stephen Brown at Stepping Hill Hospital, Stockport, has published results on 30 patients he has treated using a version of HIFU called Ablatherm. Mr Mark Emberton has commenced a trial at the Institute of Urology, London and Mr Simon Brewster is also setting up a trial at the Churchill Hospital, Oxford. These two surgeons are using a version of HIFU known as Sonablate.
HIFU would seem to have exciting potential and The National Institute for Clinical Excellence (NICE), the body responsible for providing treatment guidelines for the NHS in England and Wales, is apparently fast-tracking its evaluation of the treatment.