Hadron therapy uses sub-atomic particles to deliver radiotherapy and has the capability of delivering to an increased depth compared to photons. This offers the potential of conformal therapy without the increased integral dose associated with intensity-modulated radiotherapy (IMRT). In addition, there is the possibility of hadron therapy having increased relative biological effectiveness (RBE) when compared to photons. There is increasing interest in this topic currently with the possibility of a second UK hadron therapy facility being under discussion.

This paper introduces the concept of hadron therapy and presents an evaluation of the potential benefits associated with it. Planning studies and clinical trials are reviewed in order to assess the impact that hadron therapy would have on patient management. Costs and other factors affecting the implementation of a hadron therapy facility are presented.

The proven benefits of hadron therapy are easily demonstrated by the planning studies with increased conformity and reduced integral dose over a range of tumour sites. Simple hadron plans consistently out-perform complicated IMRT plans. The costs associated with hadron facilities are higher than for photons, but they offer simplified planning due to the inherent conformality achievable with simple hadron beams. As costs decrease and technology improves, the benefits of hadron therapy may result in the replacement of the photon for radiotherapy.