Currently a standard treatment for several gastrointestinal cancers (GI) combines the use of chemotherapy and radiation followed by surgical resection. Radiation may be part of the treatment strategy for select cancers of the esophagus, anus, rectum, pancreatic, or small intestine. This treatment approach is often associated with improved outcomes but the radiation may also cause increased side effects to adjacent organs. Doctors are evaluating whether proton beam therapy, a more precise way to deliver radiation may be a superior alternative to standard radiation therapy.
Proton therapy is similar to traditional radiation therapy, but it uses a different type of energy and is much more accurate at targeting tumors. Standard radiation therapy uses X-ray beams made up of photons, which are tiny particles that transmit light. Photons deposit energy as they travel to the tumor, into the tumor itself and beyond the tumor. This results in side effects from damage to nearby healthy tissues or organs. The dose delivered to the tumor must be limited to minimize these side effects.
Proton therapy uses protons, which are positively charged particles found in the nucleus of an atom. Proton beams enter the body with a low dose of radiation and the dose increases as it approaches the target area and deposits its maximum radiation directly to the tumor before stopping. There is no “exit dose” beyond the tumor. This means the tumor can be targeted more precisely, usually within one millimeter and allows for the delivery of a more powerful dose of radiation.
Intensity-modulated proton beam therapy with pencil scanning goes a step further, dividing a proton beam into smaller beams of varying intensity that paint radiation within the tumor. Conforming the beam more precisely to the tumor’s size and shape causes even less collateral damage.
Patients with GI cancers where radiation is part of the treatment plan may want to inquire about whether proton therapy is an option and determine if their treating institution can provide any specific outcome results for their situation.
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