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What is Proton Therapy?

Listen to James Metz, MD, speak about The Future of Cancer Care

Proton therapy may sound mysterious, but think back to high school science class — protons are positively-charged particles that are part of the nucleus of every atom. When aimed at tumors, however, protons are a particle with impressive power. Proton therapy uses a beam of protons moving at very high speeds — at about 100,000 miles per second, near the speed of light — to pummel and destroy the DNA of cancer cells, killing them and preventing them from multiplying.

Conventional radiation uses X-rays or gamma rays, high-energy electromagnetic waves. As those rays pass into the body, they begin to scatter and lose much of their energy even before reaching the tumor, like a flashlight beam spreading out and becoming dimmer in the distance. After passing through the tumor, they continue through the body — affecting not only the cancer cells, but healthy tissues along their path, frequently resulting in side effects for the patient.

But protons act differently in tissue, in ways that can help doctors treat tumors that are hard to reach or close to vital organs like the heart: They give up their energy completely once they enter the tumor, so radiation dose is limited beyond the tumor, causing less damage to healthy tissues.

Proton therapy potentially represents the best of both worlds — delivering a high dose of radiation to tumors, while at the same time limiting side effects to patients.

Why Use Protons?

  • Same tumor killing properties as X-rays
  • Decreased dose to normal tissues by 50-70%
  • Decreased side-effects and complications
  • Ability to treat tumors close to critical organs like the spinal cord
  • With X-rays, 20% of cancers come back because treatment dose was too low to be effective
  • Possibility to increase the safe dose delivered to tumors
  • Possibility of increased cure rates
  • The ability to re-treat tumors after recurrences
  • The added ability to treat benign conditions

Applications of Protons to Treat Cancers

Applications of Protons to Treat Benign Conditions


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