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Questions over proton treatment for prostate cancer

A new — and costly — treatment for cancer is under scrutiny amid concerns that it is being pushed for financial rather than clinical reasons in some cases.

Proton therapy uses a beam of protons to destroy cancer cells. In a study published today in the Journal of the American Medical Association (JAMA), Ronald Chen of the University of North Carolina at Chapel Hill and his colleagues raise questions over the use of this technique for prostate cancer. Their work shows that proton therapy seems to lead to more gastrointestinal problems than a more established treatment called intensity modulated radiation therapy (IMRT), which uses photons.

“Overall, our results do not clearly demonstrate a clinical benefit to support the recent increase in proton therapy use for prostate cancer,” the researchers write.

A review by the American Society of Radiation Oncology (ASTRO) published last month concluded that proton therapy is “an option” for prostate cancer but that “no clear benefit over existing therapy [IMRT]” has been demonstrated.

When presenting some of the work now published in JAMA earlier this year, Chen noted, “We’ve seen a rapid growth in the number of proton facilities in the US in the past five years, despite its very high costs. Yet with the data we have to date in the published literature, there does not appear to be a clear benefit of proton bean therapy compared to IMRT.”

Also published today is a piece in BMJ by US journalist Keith Epstein. This piece states that the “some people have recognised the rashness of the dash to introduce these machines, which have been described as the world’s ‘most costly and complicated medical devices’.”

But Manjit Dosanjh, life-sciences adviser at CERN — Europe’s main high-energy physics laboratory near Geneva, Switzerland — says that although the BMJ piece makes some valid points, proton therapy has a bright future and shouldn’t be condemned on the basis of the prostate results.

Dosanjh says that prostate cancer is not the cancer that most clearly benefits from proton therapy, and the rapid growth of its use in the United States may have financial drivers, given the structure of the US health-care system. “Prostate would not be the first choice for proton therapy,” says Dosanjh.

The BMJ piece acknowledges that this therapy has been shown to be beneficial for treating paediatric cancers and some brain tumours. Likewise, the ASTRO review notes evidence of benefit in some cancers of the eye and central nervous system and possible benefits over photon treatment in paediatric central-nervous-system malignancies. The review called for more evidence and clinical trials.

“We do need to have more data. Data has been hard to come by because there haven’t been many facilities,” says Dosanjh, who chairs the executive committee of the European Network for LIGht ion Hadron Therapy at CERN.

She adds, “Particle therapy has a lot to offer and it’s an extra weapon against cancer,”

UPDATE  (18 April):

Karen Kirkby, Director of Science at the Ion Beam Centre at the University of Surrey, UK, says that there is no intention of using proton therapy to treat prostate cancer in the UK National Health Service (NHS). She says, however, that “there is now sufficient evidence in the literature to convince a very skeptical UK clinical community that there is a case for the use of proton therapy for certain forms of cancer”.

Kirkby also points out that the product life-cycle costs of proton therapy are lower than some new chemotherapy treatments.

“Far from rushing into proton therapy the NHS has taken a long and considered evaluation,” she told Nature. “I think its a little unfortunate that a treatment that could benefit thousands of UK patients per annum and add another treatment option for clinicians is being dismissed because of the prostate experience in the USA.”

Related: European boost for particle therapy

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    Alfred Vismer said:

    I researched Proton Therapy thoroughly before having treatment. Like everyone I know, we are happy Prostate Cancer survivors, not so for many poor people who have had alternative treatments. As a research scientist I can not help thinking that those who bash Proton Therapy are basing their conclusions on shoddy test results, poor interpretations and bias reporting, because of self preservation and conflict of interest. Proton Therapy is getting better (IMPT) and cheaper – Korea and China. For us who would like to see all kinds of cancer beaten, this is a call for integrity, Doctors cease the in-fighting, do what is best for your patients.

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