What is proton therapy? How does it differ from other types of radiation therapy?

Many patients undergo radiation therapy as part of standard disease management. Radiation therapy kills cancer cells or slows their growth by damaging their DNA. There are two major types of external beam radiation: photon (or x-ray) based radiation and particle (proton) radiation. Proton therapy has unique physical characteristics and the potential to decease acute and late side effects associated with radiation. Protons target a patient’s tumor with sub-millimeter precision, sparing nearby healthy tissues. In contrast to photons, there is no exit dose to tissues beyond the tumor. The precision of proton therapy is especially useful in the delivery of radiation in children and in cases where a tumor is nearby or involved with critical organs. However, proton centers are expensive to build and operate, and therefore remain limited in availability.

What kind of cancer is treated with proton therapy?

Whether proton therapy is an appropriate treatment for a patient depends on many different factors, including the type of cancer, the location of the tumor, the tumor’s location in the body, and a patient’s age and medical history. Studies have shown that proton therapy can be effective in treating tumors of the brain, eye, head, neck, lung, breast, prostate, and gastrointestinal and genitourinary system, as well as cancers that cannot be completely removed by surgery. In addition to cancer, proton therapy has been effectively used to treat Parkinson’s disease, macular degeneration, arteriovenous malformations, severe rheumatologic conditions, and seizure disorders.