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Proton Beam Therapy

Proton Beam Therapy is a form of radiation therapy.

As the name implies, it uses particles with actual mass (protons), instead of electromagnetic waves as in other radiation therapies. For the treatment, these atoms are produced and accelerated in a synchroton or cyclotron and then targeted at the cancer.

The key difference to other radiation therapies is that heavy particles, as opposed to photons will stop within the target, here the cancerous tissue. At this point, interaction of the protons with the surrounding tissue will take place, causing damage within the cancer, but not beyond it. Under these circumstances, it is theoretically possible to increase radiation doses within the target while reducing the exposure in the surrounding tissues and organs.  Whether this advantage over other radiation therapies is significant or not has been a hot topic among oncologists and remains unclear to date, as completed comparison Phase III trials are lacking.

For treatments of tumors where the position of the target organ does not remain constant due to respiration and intestinal movements, as is the case for the prostate, proton beams are not seen to be superior to the established and acclaimed electromagnetic radiation methods. In addition, PBT is very complex and costly.

Genitourinary toxicity at 12m

Proton Beam Therapy: 


Gastrointestinal toxicity at 12m

Proton Beam Therapy: 


Genitourinary toxicity included infection, upper urinary tract dysfunction, urethral stricture/obstruction, incontinence, erectile dysfunction.

Gastrointestinal toxicity included fistula, rectal repair, stenosis, bowel resection, other.

Citation for PBT numbers: Yu, James B., et al. "Proton versus intensity-modulated radiotherapy for prostate cancer: patterns of care and early toxicity." Journal of the National Cancer Institute 105.1 (2012): 25-32.