Clinical controversies: Proton therapy for thoracic tumors

Photon and proton therapy techniques have both improved dramatically over the past decade. As a result, high radiation doses can be delivered while sparing organs at risk. However, in many series, older proton techniques have been compared with contemporary photon techniques, hampering a fair comparison. By virtue of their physical properties and because of modern 4-dimensional and imaging evolution, protons show theoretical superiority compared with photons. Current nonrandomized studies suggest that protons may indeed spare organs at risk much better that the best available photon techniques, leading to fewer side effects and the possibility for safe dose escalation. This is the basis for ongoing randomized trials.