## 10 Discussion and Conclusions  
Before discussing in detail where we are with laser driven ion beams for oncology, we comment briefly on possible controversies concerning the effectiveness of ion beam radiotherapy in general (_i.e._, with conventional accelerator driven proton and heavy ion beams). Two very important papers addressing this ongoing debate have recently been published [127; 128]. There is no question that charged particle radiation therapy offers significant advantages in physical dose distributions (Bragg Peak--Figure 1), however, the authors of these two papers are questioning whether better physical dose distribution necessarily results in overall clinical benefit. The conclusions of these papers strongly suggest that randomized trials would remain the preferred goal to test the effectiveness of proton and heavy ion therapy. In addition, establishing a European Hadron Therapy Register (or better, an International Register) to make better use of the data being generated by the many existing hadron therapy centers would be greatly beneficial. A further controversial article was published in the Biology and Medicine Journal (entitled \"Is spending on proton beam therapy for cancer going too far too fast\" [129]. However, in answer to this paper, a group of UK oncologists claimed the report misrepresented the approach being used in the UK [130]. [PERSON] claims that despite huge amounts of money being put into building accelerators for proton therapy the first randomized trial is just beginning and will not be completed for seven years. In this work, the essence of these considerations for the future is the development of reliable, controlled laser-driven sources (photons and particles) for medical application. Since we must wait seven years for completion of the first randomized trial that is testing the efficacy of conventional accelerator driven proton therapy, it is relevant to speculate about the anticipated state of laser-driven hadron therapy in the future. A number of articles dealing with the prospects for, and progress towards, laser proton therapy have been published especially in the last year dealing with this question [131; 132; 133; 134; 135; 136], with estimated time frames of 4-10 years or longer being suggested for implementing laser driven ion beam radiotherapy (shorter time estimates apply to ocular tumors for which required proton energies are \(\sim\)70 MeV). With appropriate targetry, contrast and focusing PW level lasers will likely accelerate proton and ion beams to kinetic energies that are relevant to radiotherapy of deep seated tumors. Over the next few years these systems will likely continue to be very large and very expensive. Thus, to deliver the vision of a compact, affordable ILDIAS much \"thinking out of the box\" could be necessary to deliver better targets, better lasers and better beam delivery. In the broader context of fully functional integrated laser-driven systems (ILDIAS and ILDEAS), it is clear that considerable progress must still be made if we hope to realize laser-driven accelerators with medically relevant beam parameters and performance levels suitable for clinical usage. Meanwhile, the path toward laser-driven energetic particle beams of medical quality will no doubt also enable other important \"en route\" applications that can serve to highlight ongoing progress and multiple laser-driven capabilities. Although many researchers at high power laser laboratories around the world make reference enthusiastically to laser-driven proton radiotherapy, time on these lasers to develop the necessary clinical requirements can be quite limited and such applications are typically treated as a lower priority. There is little doubt that realizing concrete progress toward the laser-driven radiotherapy vision requires a laser center that is dedicated to laser-driven accelerator development for radiotherapy and a variety of other applications.