Proton radiotherapy for prostate cancer: how did we get here, and where do we go from here?

Proton radiotherapy is an important technology for cancer treatment. By reducing and even eliminating unwanted radiation dose to surrounding tissue, proton therapy has the potential to lessen the toxicity of radiotherapy. The promise of precisely delivered radiation doses has led to the adoption of proton radiotherapy in selected centers across the United States.[1] Currently there are 11 proton centers in operation, with 8 centers under construction and 1 in planning. There are 11 additional smaller superconducting synchrocyclotron proton radiotherapy machines currently in development.[2] However, despite the promise of proton therapy, comparative evidence has yet to definitively demonstrate its clinical benefit over other forms of contemporary radiation for prostate cancer.