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Question: What is Proton Therapy?
Protons, along with neutrons and electrons, make up the structure of atoms. Using special machines, called cyclotrons, protons can be stripped from atoms and concentrated into a particle beam to treat tumors. Protons are different from x-ray beams, also used to treat brain tumors, in that they carry an electrical charge. This charge causes them to interact with matter in a different fashion than uncharged radiation beams like x-rays. Whereas x-ray beams gradually transfer their energy as they travel through tissue, protons transfer their energy at fixed depth in tissue. This unique property of protons provides additional opportunities to spare tissues outside an area being treated, with the potential to reduce side effects and/or to safely increase radiation dose to improve cure rates. Improvements in the technology to deliver x-ray treatments have also increased dramatically over the last decade and have also improved our ability to achieve highly focused radiation treatments to reduce side effects and increase radiation dose safely with x-ray treatments. As a result of these improvements, there is considerable controversy as to whether the physical characteristics of proton beam therapy provides any meaningful clinical benefit to patients over modern, state of the art photon beam (x-ray) radiotherapy. Currently, the facilities required for proton beam therapy are considerably more costly than those required for x-ray treatments and there are a limited number of facilities in North America providing these treatments. Ultimately, clinical studies are required to compare x-ray and proton treatments for different situations, including brain tumors, to determine the relative cost-benefits of these two technologies.
A special thank you to Dr. Glenn Bauman, Radiation Oncologist at the London Regional Cancer Program for his time in answering this important question for our readers. Dr. Baumann volunteers with Brain Tumour Foundation of Canada as a member of our Professional Advisory Group, has spoken at several Information Days, and participated at our 2008 Research Think Tank. Thank you again for all of your continued support.
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