Proton beam therapy

Vivien Williams: Standard radiation therapy is an effective way to treat many cancers but it isn’t perfect. It kills cancer cells but it also kills healthy cells in its path through the body. That is 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.

Robert Foote, M.D., Mayo Clinic Proton Beam Therapy Program: The downside to the x-rays is that they pass all the way through the body.

Ms. Williams: 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 can 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.

Steven Schild, M.D., Mayo Clinic Proton Beam Therapy Program: A proton is one of the key constituents of matter.

Ms. Williams: They are like little bullets that can be made to stop when they hit tumors.

Dr. Schild: The way it stops tumors is that 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.

Ms. Williams: This massive machine is called the synchrotron. It accelerates the proton to nearly the speed of light and fires them into the body. Here is 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 is 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.

Dr. Schild: But where you need to be very precise, where the tumor is next to something critical, like next to your eye or next to your spinal cord, that is where you’ll have a major advantage.

Dr. Foote: 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?

Ms. Williams: Proton beam therapy is particularly beneficial to children.

Dr. Schild: Pediatric tumor and tumors in children, you really want them exposed to as little radiation as possible and this means that there body will be exposed to a lower dose overall.

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

The Mayo Clinic Proton Beam Therapy Program will be ready for patients in 2015. It is the result of a gift of long-time Mayo patient and philanthropist Richard O. Jacobson.

For Medical Edge, I’m Vivien Williams.