Controversies in proton therapy for prostate cancer

Proton therapy (PT) for prostate cancer has been a subject of controversy over the past two decades. Because of its dosimetric advantages when compared to conventional radiation, PT has the potential to improve the therapeutic ratio in the management of prostate cancer by decreasing toxicity and improving disease control. Nevertheless, its higher costs and the current lack of level I evidence documenting improved clinical outcomes have led some to question its cost-effectiveness. A number of new PT centers have been built over the past decade, leading many stakeholders, including patients, physicians, and insurers, to demand comparative effectiveness data to support its current use. In this review, we summarize the results of recently published studies that support the safety and efficacy of PT in the treatment of prostate cancer. We also review the available cost-effectiveness data for PT and discuss the future of PT, including the current randomized trial comparing PT to intensity-modulated radiation therapy and the need for additional research that may help to establish the relative benefit of PT when compared to photon-based radiation therapy.