Hadron therapy often refers to proton therapy (PBT) and carbon ion therapy (CIRT) are not new technologies, but have been subject to assessment by several Health Technology Assessment (HTA) agencies over the past years. This review paper summarized the evidence findings from most recent HTA reports and provided a description of currently ongoing clinical studies. The main claimed benefit of PBT and CIRT is a reduction in toxicity compared to conventional radiation therapy, resulting in fewer harms and a lower risk of induced secondary malignancies.

The overview of available evidence for PBT is drawn from five HTA reports on a total of 16 oncology indications, including 295 primary studies of any study design. All included HTA reports concluded that the quality of research is low and that there is insufficient evidence to support the claimed benefits of PBT. This review also pointed out that there is a lack of agreement on the appropriate study design and lack of coordination between centers in the production of joint research protocols to generate the necessary evidence. This has led to the production of numerous small, poorly designed and reported studies.