Clinical Corner - June 2022

One of the exciting new initiatives being developed at my cancer program is the creation of a stand-alone radiation oncology center which will house a proton therapy unit. Although the concept of treating cancer with protons has been increasing over the last decade, there has been a paucity of these dedicated units throughout the United States. Since one of the critical goals of our cancer registries is to capture data relating to new treatment modalities, I thought a short overview dealing with proton therapy would be welcomed. 

Proton therapy is a newer type of radiation therapy that uses energy from positively charged particles (protons). A machine called a synchrotron or cyclotron speeds up protons. The high speed of these protons creates high energy which allows the protons to travel to the desired depth in the body. The protons then give the targeted radiation dose in the tumor which results in less radiation dose outside of the tumor. In conventional external beam radiation therapy, x-rays continue to give radiation doses that may damage nearby healthy tissues, possibly increasing adverse side effects. Proton therapy may also be used if the cancer remains or recurs after traditional external beam radiation.

Compared with conventional 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.

Proton therapy has shown promise in treating several kinds of cancer including CNS tumors, ocular melanoma, head and neck cancers, prostate cancer and pediatric malignancies. Clinical trials are investigating proton therapy as a treatment for several other types of cancer. Few studies, however, have compared proton radiation against conventional radiation using photons. As this form of radiation oncologic treatment becomes more widespread, the challenges of capturing data relating to this treatment will increase. Be on the lookout for a proton therapy unit near you!