Protons 105 -- Comparing the Possibility of a Secondary Cancer Caused by Radiation Treatment

We all know the dangers of radiation. When you get an xray, the technicians step out of the room. When you get dental xrays, you get a lead bib put over your sternum. Here at Loma Linda, when I receive treatment, everybody leaves but me and the the door to my room gets locked so someone can't stumble in.

The benefits of xrays in general and proton treatment in particular (should I say hypothesized or proven?) outweigh the risks. And, the technicians would be subjected to many times the dose that I receive since they do it all day long and year after year. But, it would be nice to know what the risks are.

Apparently, these risks arise from the creation of neutrons during the delivery of the protons. I gather, but have not been able to determine, that the interaction of the protons with body tissue creates neutrons. And those neutrons could cause a secondary cancer.

A study just came out which found that the risks of a secondary cancer from proton radiation are lower than for photon radiation. You can check it out at http://www.sciencedaily.com/releases/2008/09/080922122421.htm . The study notes that 6.4% of proton therapy patients got a secondary cancer. Now, I don't have the entire study and it traces patients all the way back to when proton therapy first began (1974-2001) and does not appear to be limited to prostate cancer treatment. Sooooo, take those figures with a huge grain of salt. The study also found that patients treated with conventional radiation later got a secondary cancer at exactly double the proton rate -- at 12.8%. I think it is that comparison that is the most important aspect of the study. The conventional radiation percentage has to be smaller these days also because the ability to focus conventional radiation has gotten so very much better than it was in the old days. But, again, the important finding was that proton treatment resulted in fewer secondary cancers than conventional treatment.