Proton Therapy
Proton therapy is a form of external beam radiation that uses accelerated protons instead of x-rays; protons release most of their energy at a set depth and then stop, so tissue beyond the tumor receives very little dose. In a large observational study, severe side effects were less than half as frequent as with conventional radiation, while rates of survival and cancer control were similar; phase 3 randomized trials directly comparing the two approaches are ongoing. The method requires specialized, costly equipment and is available only in a limited number of centers.
How it works
Used in
Chordoma and chondrosarcoma of the skull base and spine: NCI PDQ lists proton-beam radiation as part of standard postoperative treatment for chordoma.
Soft-tissue sarcomas in children and young adults at paraspinal and skull-base sites, where sparing critical organs and reducing second-cancer risk are decisive.
Uveal melanoma — proton-beam therapy as eye-preserving treatment and an alternative to plaque brachytherapy.
Childhood ependymoma — protons limit dose to the developing brain outside the target volume, which matters for late neurocognitive effects.
Proton craniospinal irradiation in children with medulloblastoma spares the cochlea, heart and thyroid while achieving disease control comparable to photon techniques.