Place of proton radiotherapy in future radiotherapy practice.

Proton beam therapy offers potential dosimetric advantages coupled with complexities not currently encompassed in the photon radiotherapy experience. The practice is evolving alongside other developments in oncology, which include higher precision of photon radiotherapy, greater understanding of the biological effect of radiation and its potential modification, and the recognition of new molecular targets with a plethora of agents aimed at affecting biological function. For proton therapy to have an impact on clinical practice requires full examination in rigorous clinical trials comparing proton with best photon therapy. Only the results of present and future studies, showing equivalent, superior, or even potentially worse clinical results will shape their application. The desired goal is to develop personalized treatment strategies of fractionation appropriate for protons potentially combined with targeted agents. We describe the steps in health technology assessment and the potential design of preclinical and clinical trials to define the role of proton therapy in the future.