Summary of ongoing clinical protocols for proton and heavier-ion therapy

Since 1954 when the very first patient was treated at LBNL with heavy-charged particles, some 84,000 patients in total have now been treated with protons, and another 13,000 patients have been treated with carbon and other heavier ions. During the first several decades of this endeavor, particle therapy was accessible only at a small number of programs. More recently, however, this therapy has become available at a rapidly increasing number of facilities worldwide. This expansion of the discipline has led to the development of many more clinical trials, designed to optimize particle-beam therapy and to compare the results achieved with those resulting from other treatment methods. Presently, more than 50 clinical protocols worldwide are actively involved in the effort to improve our understanding of these clinical guidelines. The purpose of this brief review is to offer a broad overview of these protocols, highlighting the specific disease categories that are now being studied using proton and/or heavier-ion therapy, and how the parameters of dose-escalation, beam conformity, and RBE modeling are being evaluated for various disease sites and stages.