L52 — December 2011 — Proton Beam Therapy

Intro: Standard radiation therapy is an effective way to treat many cancers. But it isn't perfect. It kills cancer cells, but it also kills some healthy cells in its path through the body. That's just one of the reasons Mayo Clinic is bringing a new type of radiation therapy to its patients. It's called proton beam therapy, and it has the potential to cure more cancers with greater safety and help people live longer.

Doctors have used radiation therapy to kill cancer cells for many years. The standard technology fires X-rays, or photons, at tumors in hopes of eradicating them.

The downside to the X-ray is that they pass all the way through the body.

Mayo Clinic Dr. Robert Foote says that means the radiation also kills healthy cells. This limits how much radiation you can safely give to patients because it could damage surrounding tissues and organs. But a new technology called proton beam therapy is more precise and therefore more effective. Dr. Foote and Dr. Steven Schild head the Mayo Clinic Proton Beam Therapy Program.

A proton is one of the key constituents of matter.

They're like little bullets that can be made to stop when they hit tumors.

The way it stops in tumors is you have to aim it properly, and you have to give it the proper amount of energy so it stops in just the right place.

This massive machine is called a synchrotron. It accelerates the protons to near the speed of light and fires them into the body. Here's how proton beam therapy compares to conventional radiation therapy. The X-rays of conventional radiation therapy radiate everything in their path — structures both in front of and behind the tumor. The proton beams of intensity-modulated proton beam therapy can be better controlled, in both width and depth. The technology aims the proton beams with what's called pencil beam scanning. It "paints" the beam back and forth through the tumor. Because the beam does not go beyond the tumor, doctors can deliver higher doses of radiation without damaging surrounding tissues.

Where you need to be very precise or the tumor's next to something that's critical, like next to your eye or next to your spinal cord, that's where you'll have a major advantage.

Since this is so accurate and so precise, can we give a larger dose of radiation with each treatment and give fewer treatments? Can we convert a nine-week course of treatment into a one-week course of treatment?

Proton beam therapy is particularly beneficial to children.

For pediatric tumors and tumors in children, you really want them exposed to as little radiation as possible, and this means that their body will be exposed to a lower dose overall.

Proton beam therapy. A way to target tumors more precisely to help more people with cancer live longer.

For Medical Edge, I'm Vivien Williams.

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The Mayo Clinic Proton Beam Therapy Program will be ready for patients in 2015. It's the result of a gift from longtime Mayo patient and philanthropist Richard O. Jacobson.

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