In contrast to radiation therapy, which works with electromagnetic radiation (photons), proton therapy uses hydrogen atomic nuclei (protons) to "shoot" at the tumour. With the help of a particle accelerator, protons are accelerated to about two thirds of the speed of light; that is about 180,000 km/second. They are then able to penetrate the body by just under 40 cm. When entering the body, the beam is not absorbed but decelerated. The slower the particles become, the more energy they emit. The speed of the protons is controlled in such a way that the energy maximum (Bragg peak) is reached in the target tissue. The ionising effect of the protons then leads to damage to the tumour cells, especially their DNA. However, a tumor must be "bombed" several times in order to reach all areas of the abnormal cells.
Long-term data poor - not suitable for prostate cancer
The German Society for Radiooncology (DEGRO) sees a high need for research in proton therapy with regard to tumor control, survival rate, complications and late effects. Very little knowledge is available about long-term results and chances of recovery. Up to now, treatment with protons has only made sense for a few tumor types - for example in the cranial base area. In the case of tumours - such as prostate carcinoma - in which the position of the target organ (prostate) does not remain constant due to respiration and intestinal movements, proton beams are not superior to the established and tested electromagnetic radiation. In addition, proton therapy is very complex and cost-intensive compared to established irradiation methods.