- SEATTLE -- An invisible knife
that uses high-intensity sound waves to penetrate the body and destroy
tumours is set to revolutionise cancer treatment, it is claimed.
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- In five to 10 years ultrasound could replace conventional
surgery and radiotherapy for patients with many different types of cancer,
scientists said.
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- The technique is undergoing early trials for liver and
kidney cancer in the UK while a French team using a different system has
already achieved disease-free results treating men with prostate cancer.
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- In China, where the technology has been pioneered, anecdotal
evidence from studies of thousands of patients is said to be "astounding".
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- Ultrasound surgery focuses bursts of high energy sound
waves on the tumour, heating it to a temperature of 60C. The tumour cells
are destroyed while surrounding tissue is left unharmed.
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- Professor Gail ter Haar, who is leading trials of an
experimental system at he Royal Marsden Hospital in Sutton, Surrey, said
the technique could treat tumours up to the size of a small orange.
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- At this stage the trials are confined to testing the
safety of the technique, but Prof ter Haar said they had already yielded
"really exciting results".
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- She told the American Association for the Advancement
of Science's annual meeting in Seattle yesterday: "I think there will
be cancers for which it will revolutionise treatment, but we're a long
way from knowing which they will be, and exactly how it should be employed."
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- Patients with liver and kidney cancer are taking part
in the Royal Marsden studies. Treatment consists of two-second long bursts
of ultrasound delivered to the surface of the body by a machine mounted
on a gantry. A number of bursts are needed to clear an organ of cancer.
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- At a different centre in Oxford, Prof ter Haar has been
using a commercial device developed in China to treat a similar group of
patients.
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- She has worked with Chinese physicians who have already
treated about 3,000 cancer patients with ultrasound. Although the Chinese
trials were not as scientifically rigorous as those in the UK, the anecdotal
evidence was impressive.
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- "The results in China are really quite astounding,"
said Prof ter Haar.
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- "There are patients who are disease free with tumours
for which there are no other treatments, particularly in the pancreas."
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- She said that theoretically ultrasound should be suitable
for a wide range of solid tumours.
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- "If you can image a tumour with diagnostic ultrasound
you should be able to treat it," she told the meeting.
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- However since the sound beam could not travel through
bone or air, certain cancers would be difficult to treat. Brain tumours
and lung cancers deep behind the rib cage fell into this category.
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- Scientists in the UK and United States were working on
the problem of getting ultrasound into the brain.
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- "Its very appealing for the brain because it's a
trackless form of damage," said Prof ter Haar. "You only get
damage at the focus so you don't damage the rest of the brain through which
you've got to travel. If we could solve that problem it would be very exciting."
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- Dr Jean-Yves Chapelon from the French research institute
Inserm in Lyon described a different ultrasound system now at an advanced
stage of development which he had used to treat 242 men with prostate cancer.
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- The results were due to be published in the next few
months. Dr Chapelon said the treatment was as effective as conventional
surgery or radiotherapy, and safer.
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- In this case the ultrasound beam was delivered through
the rectum. After five years of follow-up, 80% of low-risk patients were
found to be disease-free and effectively cured. For medium-risk patients
the success rate was 60% and for patients with high-risk aggressive cancers,
50%.
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- The men had an average age of 71. Traditional treatments
for older men with prostate cancer carry a high risk of impotence and urinary
incontinence, but 40% of the patients recovered their potency and only
8% were unable to control their urine flow.
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- Not one patient had died of cancer although the first
was treated as long as 11 years ago.
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- "We believe that this therapy challenges other therapies,"
said Dr Chapelon.
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- However, he said that at present it was still difficult
to convince specialists that ultrasound therapy could be as good as conventional
treatment.
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- Prof ter Haar said said there was still much work to
do before ultrasound became universally available as a cancer treatment.
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- She expected the process of patient trials, publication
of data, and introduction into hospitals to take between five and 10 years.
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- Another possible application of ultrasound might be on
the battlefield, according to Dr Shahram Vaezy, from the University of
Washington in Seattle.
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- His team was working on miniaturising ultrasound equipment
that could be used to treat wounded soldiers, or accident victims.
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- A big advantage of ultrasound was that it had the ability
to stop bleeding by sealing broken blood vessels, he said.
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- Dr Vaezy told the meeting: "The application we are
pursuing is treating internal bleeding, to develop a non-invasive method
of treating patients at the scene of an accident, for example."
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- ©2004 Scotsman.com
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- http://news.scotsman.com/latest.cfm?id=2533743
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