For many years we treated prostate cancer thirty times or forty times in a month. For many years we would use what we call 2Gy per fraction, that was the standard size of the radiation or dose of the radiation. So we would do more than 30-40 treatments. A number of advances have happened in the last few years – the British did a study where they showed that you could reduce the number of treatments down to about twenty. By using more sophisticated technology we are now treating patients with as few as four fractions of radiation and we use something that we call stereotactic body radiotherapy. You can use linear accelerators which are traditional radiation machines or you can use something called a CyberKnife device which is made by one company. These are stereotactic ways to do very precise radiation. I tell my patients that it’s sort of like when you go to buy a car – you can pay cash for the car, say it costs you $50,000, or you can finance it over seven years and it costs you $80,000. So when you do radiation over eight weeks the total dose is higher but you’re paying a little bit at a time; when you use stereotactic techniques you can do it in four treatments and the results appear to be as good or maybe better.

That’s pretty well established now in the United States. What we’re interested in doing now is trying to use alternative forms of radiation, including protons and carbon radiation in addition to X-ray radiation. So the first example I gave of using 30-40 treatments was with X-rays; there are more sophisticated forms of radiation which involve particles, charged particles. These charged particles have advantages because they don’t have exit dose. The radiation comes in and the radiation stops; the X-rays always have exit dose. Also, the scatter, when the beam comes in the beam has a certain amount of fuzziness to the edges, the particles the beam is less fuzzy. So protons are tighter, less fuzzy, than X-rays and the beam stops. Carbon, in addition to being even tighter than protons has a higher radiobiological effectiveness which we can quantify. For example, if protons have a radiobiological effectiveness of 1 then carbon is estimated to have a radiobiological effectiveness of 3.

So we think that one day we will be able to treat prostate cancer with less side effects using particles.