Objective: To provide an overview of the present role of proton and ion therapy, also referred to as 'charged particle therapy', in the treatment of cancer.
Design: Systematic literature study.
Method: Systematic electronic searches were carried out in 12 databases according to the Cochrane Collaboration criteria, without restriction as to year of publication or study design. Manual searches of bibliographies and journals were also performed. The inclusion criteria were: at least 20 patients and a follow-up of at least 2 years. In addition, experts on the subject were consulted by correspondence for their opinion.
Results: The search identified 36 relevant articles on proton therapy and 15 on ion therapy. Based on prospective and retrospective studies, proton irradiation emerged as the treatment of choice for ocular tumours, chordomas and skull-base tumours. For prostate cancer, the results were comparable with the best results of photon therapy. Ion therapy was still in an experimental phase.
Conclusion: According to the current literature, proton therapy is looked upon as the preferred treatment modality for certain rare tumours, such as ocular tumours, chordoma, and skull-base tumours. However, charged particle therapy as a whole, and especially ion therapy, is not supported as the treatment of choice for cancer by published evidence. Nevertheless, the potential theoretical benefit of this treatment is great.