What Is Proton Therapy?

Proton therapy is an advanced, powerful alternative to standard radiation treatment for cancer that targets tumors directly while minimizing radiation exposure to healthy tissue. Proton therapy allows doctors to zero in on the tumor and provide a higher dose of radiation that’s delivered only to the cancerous cells, protecting the healthy tissue surrounding the tumor and reducing both short- and long-term side effects that are normally associated with standard radiation treatment.

These differences make proton therapy an ideal way to treat pediatric cancers and tumors of the brain, spinal cord, breast, gastrointestinal system, lung, and prostate.

How Does Proton Therapy Work?

Proton therapy is a type of radiation therapy. Both proton therapy and standard radiation work by changing the molecular structure of cancer cells to prevent them from growing and reproducing. Both treatments work to eradicate tumors and cancer cells – the difference is in the type of radiation the way that radiation is delivered.

How Does Proton Therapy Work

Standard x-ray radiation uses photon rays that have to both enter and leave the body so the maximum dose of radiation is released as soon as it penetrates the skin, which can damage healthy tissues and organs on both sides of the tumor.

Proton therapy uses protons, high-energy radiation that is more targeted than the photons used in standard radiation. Because protons can be used with more precision, doctors can target tumors directly and set the proton beam to release radiation when it gets to the tumor, sparing the healthy tissue surrounding the tumor from radiation exposure.

Doctors use three-dimensional mapping to set the exact depth of the proton beam to the tumor location so maximum radiation energy will be released only within the tumor. This point of maximum energy release is known as the Bragg Peak. The proton beam and Bragg Peak can be adjusted to match each patient’s specific treatment needs depending on the location, depth, shape, and size of the tumor so healthy tissue around the tumor is protected. In fact, once the protons hit the tumor and reach the Bragg Peak, the radiation falls to almost zero. This means not only is there low exposure to tissue in front of the tumor, there is almost no exposure to the tissue behind it.

What Kinds of Cancer can Proton Therapy Treat?

Proton therapy is effective in treating a variety of cancers, including tumors of the brain, spinal cord, breast, gastrointestinal system, lung, and prostate as well as pediatric cancers. Because the precision of proton therapy allows doctors to use higher doses of radiation to attack the tumor without damaging the surrounding area, it’s frequently used to treat tumors close to the spinal cord or vital organs.

For pediatric cancers in particular, proton therapy is often a better option than traditional radiation therapy because protecting healthy tissue is even more important when the body is still growing. Side effects for children associated with traditional radiation therapy include complications in growth and IQ development. Clinical studies have shown proton therapy reduces these risks as well as the risk of additional tumor growth in the future.



Proton therapy may not be appropriate for all types of cancers and patients. Proton therapy is typically most effective for tumors that are localized and well defined, meaning they have not spread to other areas of the body. If a tumor has spread, or metastasized, your doctor will work with you to decide if proton therapy is still an option. In general, because each patient’s needs are different, your doctor and healthcare team will work closely with you to determine the best course of treatment.