Proton therapy is the most precise and
concentrated form of radiation therapy to treat cancer.
For over a
century, ionizing radiation has been effectively used to treat cancer. Since its inception, radiation oncologists have
sought to improve their ability to deliver precise doses of ionizing radiation
to cancerous targets while minimizing the dose to normal tissues. This is known
as the “as low as reasonably achievable” (“ALARA”) principle.
x-ray radiation damages healthy cells in front of and behind the tumor. This excess radiation damages healthy tissues
and can cause undesirable side effects including new cancers.
are more precise and
concentrated than X-Ray radiation.
Proton beams have a special property called the “Bragg Peak” which
allows oncologists to deposit nearly all of its energy directly on the
tumor. Protons not only reduce radiation exposure to healthy tissue, but they deliver a higher concentrated dose to the tumor.
Figure 1: A graphic illustration of the Bragg-Peak effect. Proton beams can be directed to release the majority of their energy at a desired tissue depth to maximize clinical impact. Note that the proton entrance and exit dose is much lower than the photon (XR) dose.
Figure 2: A side-by-side dose distribution map for a craniospinal patient receiving proton therapy vs. photon (X-Ray) therapy.
Safe & Effective
For over 25 years,
leading US institutions have treated cancer patients with proton therapy. Almost a million patients in the US have
cancers that can be treated with protons. Dozens of studies are published every year which highlight the
therapy’s safety and clinical efficacy.
Proton therapy is very targeted and is used to shrink tumors that have not yet spread to other parts of the body. Proton therapy is especially useful for treating a tumor next to critically important tissues, such as optic nerves, that need protection from radiation damage. Doctors may use proton therapy alone, or they may combine it with surgery, additional radiation and/or chemotherapy.
Proton therapy is great for pediatric cancer patients because it lessens the
chance of harming healthy, developing tissue. Children may receive proton
therapy for rare cancers of the central nervous system (brain and spinal cord)
and the eye, such as retinoblastoma and orbital rhabdomyosarcoma.
Researchers are studying proton therapy for cancer for other parts of the body, including breast cancer, esophageal cancer, pancreatic cancer, rectal and anal cancer, and sarcoma.