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Proton Beam Therapy: The legacy of the Ashya King Case

In 2014 a media storm was whipped up around the case of Ashya King. The young boy, who had been diagnosed with a medulloblastoma, was taken abroad by his parents against medical advice. The reason? So he may undergo treatment that was not available in the UK known as proton beam therapy (PBT).

Since then the NHS has planned to open two new proton beam therapy centres. One at the world famous Christie Centre in Manchester and another at the equally world-renowned UCL Hospital in London. Private companies are also investing in centres across the country. Proton Partners International, announced the arrival of an accelerator machine in Newport, Wales last month. So why after so much controversy has the UK finally given this new therapy the go ahead?

Radiotherapy

Radiotherapy is currently one of the mainstays of treatment for cancer. The aim of which is to destroy cancerous cells with high energy beams. Whilst this process can be life-saving, it can also cause many devastating side effects in the immediate phase and beyond. In the treatment of medulloblastoma, this can include life-altering hearing loss. This occurs as healthy cells are damaged by the beams along with the cancerous cells.

Proton Beam Therapy

Whilst radiotherapy indiscriminately damages all cells whether they are cancerous or not, proton beam therapy is selective. The protons (subatomic particles) only kill the target cancer cells as their large mass scatters less energy. This leads to fewer healthy cells being irradiated. Up until  2014 there were very few reliable control trials showing that PBT changes outcomes or improves survival. This might go some way to explaining the reluctance of Ashya’s doctors for him to be taken abroad. The NHS, however, was and still is funding treatment abroad with proton beam therapy in selected cases. The criteria for treatment is very specific and is usually reserved for young children with brain tumours, like Ashya’s case, or adults with tumours in delicate areas such as the optic nerve.

So what has changed?

The case of Ashya King itself, as well as further research into the treatment in question, has probably swayed opinion. One important trial showed that proton based therapies had a similar survival outcome to radiotherapy. There were, however, some noticeable differences between the side effect profiles of conventional radiotherapy and PBT. When treating medulloblastomas only 16% of patients receiving PBT developed significant hearing loss 5 years post treatment compared to 24% of patients receiving conventional radiotherapy.

Will PBT replace conventional radiotherapy?

Not for the foreseeable future. The treatment is still in its early stages and much research is required to establish what the long term effects are. The establishment of PBT centres within the UK will further help to facilitate this research whilst providing a beneficial service for a wide range of patients.

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Disclaimer

Any opinions above are the author’s alone and may not represent those of his/her affiliations. Any comment is based on the best available evidence at the time of writing.  All data is based on externally validated studies unless expressed otherwise. Novel data is representative of the sample surveyed. An online recommendation is no substitute for seeing your own doctor and should not be taken as medical advice. Article proofed and edited for publication by Dr Hannah Arnstein

Image sourced from pixabay

Sources and further reading

http://www.independent.co.uk/voices/comment/ashya-king-this-story-isnt-quite-what-it-seems-9716486.html (An article from 2014 about the Ashya King case)

http://www.macmillan.org.uk/information-and-support/brain-tumours/understanding-cancer/types-of-brain-tumour/medulloblastoma.html (More information about medulloblastoma from Macmillan cancer research)

http://www.nhs.uk/news/2014/09September/Pages/what-is-proton-beam-therapy.aspx(NHS information on PBT)

http://www.christie.nhs.uk/services/i-to-q/proton-beam-therapy/ (Information on PBT from the Christie Centre)

https://www.uclh.nhs.uk/aboutus/NewDev/NCF/PBT/Pages/Home.aspx (UCLH’s developing PBT facility)

http://www.proton-int.com/ (Proton Partners company website)

http://www.telegraph.co.uk/news/2017/05/20/uk-get-first-proton-therapy-centre-ashya-kings-plight-raised/ (Arrival of new accelerator in Wales)

http://www.nhs.uk/conditions/Radiotherapy/Pages/Introduction.aspx (NHS information on radiotherapy)

http://www.nhs.uk/conditions/cancer/Pages/Introduction.aspx (NHS information on cancer)

http://www.nhs.uk/Conditions/Hearing-impairment/Pages/Causes.aspx (NHS information on hearing loss)

https://www.britannica.com/science/proton-subatomic-particle (Britannica entry on protons)

https://www.england.nhs.uk/commissioning/spec-services/highly-spec-services/pbt/ (PBT commissioning information)

https://medlineplus.gov/opticnervedisorders.html (optic nerve disorders)

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About nesemsalali (10 Articles)
Medical Doctor interested in Health Journalism. Outside of medicine I am guilty of impulsive book buying.

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