Speaker 1: Welcome to Brainstuff from how Stuff Works dot com where
Speaker 1: smart Happens. I am Marshall Brain with today's question, what
Speaker 1: is proton therapy and how does it work? Imagine that
Speaker 1: you were to be diagnosed with something like breast cancer,
Speaker 1: brain cancer, or prostate cancer. Up until now, your options
Speaker 1: have been fairly limited and fairly uncomfortable. The most common
Speaker 1: first line of attack is surgery. A surgeon cuts out
Speaker 1: the tumor as best he or she can. In the
Speaker 1: case of breast, brain, and prostate cancer, this approach can
Speaker 1: be fairly problematic. In the case of breast cancer, a
Speaker 1: woman may lose one or both of her breasts. In
Speaker 1: the case of brain cancer, parts of the brain can
Speaker 1: be damaged in the process of getting to the tumor,
Speaker 1: or the tumor may not be accessible at all. In
Speaker 1: prostate cancer, the patient is often left incontinent and impotent.
Speaker 1: In surgery is usually followed by chemotherapy to kill any
Speaker 1: remaining cancer cells. Chemotherapy is a drug cocktail that is
Speaker 1: in essence poison. The poison kills the cancer cells by
Speaker 1: targeting cells that reproduce rapidly. The side effect is that
Speaker 1: other cells in the body that happen to reproduce rapidly
Speaker 1: like hair follicles, and the cells lining the stomach often
Speaker 1: suffer as well. This explains the hair loss and nausea
Speaker 1: that often accompanies chemotherapy. Another possibility is X ray therapy,
Speaker 1: where multiple beams of X rays penetrate the body and
Speaker 1: intersect at the tumor. The tumor receives a high enough
Speaker 1: dose of X rays to damage the cancerous DNA and
Speaker 1: kill the cancer cells, but there can be collateral damage
Speaker 1: at the places where the X ray beams enter the
Speaker 1: body and overshoot the tumor. Healthy tissue near a tumor
Speaker 1: often gets damaged as well. There are other therapies, including
Speaker 1: bits of radioactive serial commonly called seeds, embedded in and
Speaker 1: around the tumor in the hope of killing the tumor
Speaker 1: with nuclear radiation, various new and experimental drugs targeting things
Speaker 1: like tumor blood supply, and so on. Most of the
Speaker 1: techniques in use today have side effects that can be
Speaker 1: quite unfortunate for the patient. This is why so many
Speaker 1: people are getting excited about proton therapy. The idea here
Speaker 1: is to use protons, which have been accelerated to near
Speaker 1: light speed in a particle accelerator to kill cancer tumors.
Speaker 1: The advantage of proton therapy is a good success rate
Speaker 1: with a low incidence of side effects. So what is
Speaker 1: a proton? If you think of a hydrogen atom, the
Speaker 1: proton is the some atomic particle at the core of
Speaker 1: the atom. A normal hydrogen atom has an electron orbiting
Speaker 1: that proton. By stripping off the electron and leaving behind
Speaker 1: a bare hydrogen nucleus, you have a proton that can
Speaker 1: be used for proton therapy. Protons are so small that
Speaker 1: they can fly through the body doing very little damage,
Speaker 1: but they do slow down as they make their way
Speaker 1: through tissue. Eventually, the protons come to a stop. Add
Speaker 1: or near the stopping point, protons strip electrons off of
Speaker 1: nearby atoms, changing important molecules in the process. If a
Speaker 1: doctor delivers enough protons to a tumor, cells inside the
Speaker 1: tumor die because of this electron activity. Some doctors described
Speaker 1: protons as acting like a firecracker, avoiding damage to tissue
Speaker 1: surrounding the tumor, but exploding inside the tumor. The reason
Speaker 1: is that protons do damage when they come to rest,
Speaker 1: So if they come to rest inside the tumor. The
Speaker 1: tumor is the only thing to get significant damage from
Speaker 1: the protons. The depth that the protons penetrate into the
Speaker 1: body can be controlled by their speed. Compared to X
Speaker 1: ray therapy, there is no exit dose that can harm
Speaker 1: healthy tissue beyond the tumor, and there's only a very
Speaker 1: small entry dose. The two big problems with proton therapy
Speaker 1: right now are the fact that it is so new
Speaker 1: and the cost. There are only a handful of proton
Speaker 1: therapy facilities in the United States at the moment, and
Speaker 1: these facilities are incredibly expensive, costing hundreds of millions of
Speaker 1: dollars to build. The cost is coming from the need
Speaker 1: for a complete, highly sophisticated particle accelerator at each facility.
Speaker 1: The particle accelerator creates the protons and then accelerates them
Speaker 1: to the precise speed needed to reach the tumor. Another
Speaker 1: problem is the high number of visits. A typical prostate
Speaker 1: cancer tumor might require forty daily visits to a proton
Speaker 1: therapy facility over the course of two months, unless you
Speaker 1: happen to live in the rare city that has a facility.
Speaker 1: This means a long daily commute or a two month
Speaker 1: hotel stay along with the cost of the forty sessions,
Speaker 1: which can rise into the pends of thousands of dollars.
Speaker 1: The hope is that technological advances will lower the cost
Speaker 1: of new facilities, making the treatment much more accessible and
Speaker 1: less expensive. If that happens, it could open a new
Speaker 1: era in cancer treatment. For more on this and thousands
Speaker 1: of other topics, doesn't how stuff works dot com and
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