Proton therapy, also called proton beam therapy, is a type of radiation therapy. It uses protons rather than x-rays to treat cancer. A proton is a positively charged particle. At high energy, protons can destroy cancer cells. Doctors may use proton therapy alone. They may also combine it with x-ray radiation therapy, surgery, chemotherapy, and/or immunotherapy. Like x-ray radiation, proton therapy is a type of external-beam radiation therapy. It painlessly delivers radiation through the skin from a machine outside the body.How proton therapy works :
A machine called a synchrotron or cyclotron speeds up protons. The high speed of the protons creates high energy. This energy makes the protons travel to the desired depth in the body. The protons then give the targeted radiation dose in the tumor. With proton therapy, there is less radiation dose outside of the tumor. In regular radiation therapy, x-rays continue to give radiation doses as they leave the person's body. This means that radiation damages nearby healthy tissues, possibly causing side effects. What to expect People usually receive proton therapy in an outpatient setting. This means they do not need to have treatment in the hospital. The number of treatment sessions depends on the type and stage of the cancer. Sometimes, doctors deliver proton therapy in 1 to 5 proton beam treatments. They generally use larger daily radiation doses for a fewer number of treatments. This is typically called stereotactic body radiotherapy. If a person receives a single, large dose of radiation, it is often called radiosurgery.
Proton therapy also may be used to treat these cancers:
Central nervous system cancers, including chordoma, chondrosarcoma, and malignant meningioma
Eye cancer, including uveal melanoma or choroidal melanoma
Head and neck cancers, including nasal cavity and paranasal sinus cancer and some nasopharyngeal cancers
Spinal and pelvic sarcomas, which are cancers that occur in the soft-tissue and bone
Noncancerous brain tumors
Risks and benefits :
Compared with x-ray radiation therapy, proton therapy has several benefits:
Usually, up to 60% less radiation can be delivered to the healthy tissues around the tumor. This lowers the risk of radiation damage to these tissues.
It may allow for a higher radiation dose to the tumor. This increases the chances that all of the tumor cells targeted by the proton therapy will be destroyed.
It may cause fewer and less severe side effects such as low blood counts, fatigue, and nausea during and after treatment.
But there are also some drawbacks to proton therapy:
Because proton therapy requires highly specialized and costly equipment, it is available at just a few medical centers in the United States.
It may cost more than x-ray radiation therapy. Insurance provider rules differ about which cancers are covered and how much a person needs to pay. Talk with your insurance provider to learn more.
Not all cancers can be treated with proton therapy.
Several ongoing clinical trials are comparing x-ray treatments to proton treatments. A clinical trial is a research study that involves people. These 2 treatments are being studied for several reasons:
There may be a higher risk of not giving a large enough dose when compared with x-rays in moving organs, such as the lung.
Proton therapy has been useful in treating certain cancers. But advanced x-ray treatments for other cancers have seen excellent results with a low risk of major side effects. For these tumors, clinical trials are needed to find out whether proton therapy is better than x-rays. This is important because of the higher cost of proton therapy.