Proton beam therapy (PBT) is a form of radiotherapy that is used to treat certain cancers. Radiotherapy can also be delivered using photon treatment. Both forms of radiotherapy treatments are used to treat sarcoma and have advantages and disadvantages. Your clinical team will decide which form of radiotherapy treatment is best for you. In sarcomas PBT is usually used for patients with sarcomas in or around the spine, pelvis and for children and young adults with sarcomas. More information about which cancers are treated with PBT is available from NHS England website. For more information about the UCLH PBT centre is available here