Michael Pollitt 

Beaming in on a deadly disease

Once the stuff of science fiction, charged particle beams are being used in the fight against cancer, says Michael Pollitt.
  
  


In the past, Karen Kirkby didn't think about people with cancer. The physicist, at the University of Surrey's Ion Beam Centre, likes to work with beams of charged sub-atomic particles like protons that travel at millions of miles an hour.

But then cancer entered her life, changed her views, and has since taken her scientific research into new directions. "I wasn't really that interested in cancer until several of my very good friends got cancer. I got very angry," Kirkby says.

A chance discussion with a clinician skilled in x-ray radiotherapy then showed how her 20-year expertise with ion beams might help make a real difference for cancer sufferers. Her anger has now been harnessed into a determination to develop new charged particle beam therapies for cancer treatment. And the clinicians she regularly meets are equally passionate about their work, helping to inspire her even more.

Kirkby now heads an Engineering and Physical Sciences Research Council funded UK network on the biomedical applications of ion beams. It brings together expertise from a wide range of disciplines, enabling people like physicists, clinicians, and molecular biologists to share knowledge and work together towards a common goal.

This network of like-minded scientists, along with her new research interests, has also led to a new collaboration between the university's ion beam centre and the Gray Cancer Institute. Backed by the Wolfson Foundation, the £1.2m research project will see the opening of the world's first vertical nano-irradiation and analysis facility by June 2007.

Understanding radiation

The 20m-long experimental beam line - which is not suitable for treating cancer patients - is designed to produce a 10 nanometre diameter scanning ion beam to focus onto individual cellular structures. Not only will it help understand the way radiation affects living cells, but it will also map them in 3D and even see reactions between drugs and radiation.

It will be capable of scanning 100,000 cells per hour. "Protons are the favoured route but we want to look at the effects on cells of other ions," Kirkby says. "We can then compare the effects of protons with the heavier ions."

A proton is a positively charged hydrogen ion, just one of a range of heavier ions up to neon in the periodic table that the new beam line - a synchrotron - will produce at different energies. The objective is to destroy cancerous tissue without harming anything else - one of the drawbacks with conventional x-rays.

A phenomenon known as the Bragg Peak means that the ion's destructive energy is dissipated onto a pre-selected target - the cancerous cells - leaving other tissues unaffected. Although using proton therapy is not new for cancer treatment, the beam line will break fresh ground in trying to find novel treatment strategies.

Using actual data from experiments, computational research will construct virtual tumours and help devise treatment strategies including low doses for hypersensitive cells and examine phenomena such as the bystander effect - irradiate one cancerous cell and its neighbours may die too.

"We are doing the basic research that will underpin the next generation of proton therapy," Kirkby says. "I would hope that we will be making some significant discoveries in the next three years. I really believe that this is something that could enhance life for a lot of people."

Cancer specialist Professor Bleddyn Jones of University Hospital Birmingham wishes he already had a more powerful proton therapy machine. As a consultant in clinical oncology and applied radiobiology, he has a woman patient in her 40s with a recurrent chondrosarcoma of the skull base - a rare and aggressive cancer of cartilage that's already undergone eight hours of neurosurgery.

"There is a small residual tumour and I want that obliterated before it grows up to be larger," Jones says. He hopes to send his patient to the proton beam unit at the Massachusetts General Hospital in Boston where 300 patients with the same type of cancer have been treated with a 98% success rate.

The Department of Health ended its central fund for such treatment in March this year, so the patient's local primary care trust (PCT) put up £75,000. This leaves a £20,000 shortfall for his patient to find, so Jones says she will turn to charities for help. The absence of suitable UK proton facilities has driven Jones to write numerous papers to medical journals, go to conferences and meet like-minded clinicians.

Jones recently paid his own way to a particle therapy conference in Zurich to speak to more fortunate colleagues working at treatment centres in Europe. There are around 30 centres worldwide which have treated some 40,000 patients, so UK cancer patients have very good reason to feel disadvantaged.

Therapy facilities need funding

Jones and his co-author on several articles, oncologist Neil Burnet of Addenbrookes Hospital in Cambridge, are trying hard to convince the UK government to fund new proton therapy facilities. Planned research work at the Surrey ion beam centre will underpin any new clinical centre with an excellent understanding of the basic science.

Asked what's needed, Jones points to the new $125 million (£65.5m) Proton Therapy Centre at the University of Texas MD Anderson Cancer Centre in Houston. One of several centres in the US, it's the largest and most sophisticated facility in the world, capable of treating more than 3,000 patients a year by working long hours. Shaped ion beams precisely target cancers located by medical imaging.

A report prepared by a group of experts - including Jones and Burnet - for the Department of Health's National Radiotherapy Advisory Group in April calls for two new purpose-built proton therapy centres in this country. Although capital costs are high, this is offset by a likely 30-year operating life.

The report also includes a detailed breakdown of serious cancer types affecting around 1,900 patients a year who would benefit from safer proton therapy. And depending on clinical trials, treatment for other cancers might substantially increase patient demand.

The report is now in the hands of Professor Michael Richards, National Cancer Director at the Department of Health - the government's cancer czar. "The National Radiotherapy Advisory Group is currently considering the case for high energy proton therapy," says Richards, who hopes to report to ministers on priorities for future development in the autumn. "This is being considered alongside other aspects of radiotherapy including the need for increased capacity of standard radiotherapy,"

As the government decides what to do, the research at Surrey University into next-generation proton therapy will become increasingly important. Jones reckons that physics will enable biology as focussed nanobeams offer a better way to understand the mechanisms of radiation at cellular levels. This will help take advantage of the earlier detection of cancers, thanks to improved medical imaging. "If you find a small cancer with a high degree of confidence, that puts the onus back on physics or surgery to eradicate it," Jones says.

But using physics rather than surgery depends on having the right proton therapy facilities available. Time has all but run out for the government's decision as estimates show that several thousand cancer patients will require expensive treatment abroad.

To avoid the problems facing Britain's cancer sufferers, building new proton therapy centres seems very well justified.

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