Proton beam therapy
Proton beam therapy is an advanced form of radiation treatment that uses protons rather than traditional X-rays to target and destroy cancer cells. It is primarily employed for treating a variety of solid tumors, including cancers of the brain, breast, lung, prostate, and pancreas. This therapy is designed to minimize damage to surrounding healthy tissues, making it a compelling option for patients, particularly for tumors located near vital structures. Proton therapy can be used as a standalone treatment, in conjunction with surgery, or alongside other cancer therapies.
The procedure involves accelerating protons using a synchrotron and directing them precisely at the tumor. This targeted approach can result in fewer side effects compared to conventional radiation therapy, although some patients may still experience nausea, fatigue, or other symptoms. Success rates can differ significantly based on the type and stage of cancer, with long-term remission being a key indicator of success. Although once viewed as experimental, proton beam therapy is now widely accepted and available at numerous facilities across the United States. Nonetheless, it continues to be a topic of ongoing research and discussion within the medical community.
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Proton beam therapy
DEFINITION: Proton beam therapy, also known as intensity-modulated proton therapy or simply proton therapy, delivers targeted radiation therapy using protons instead of the electrons used by traditional radiation therapies.
Cancers treated: Brain, breast, eye, esophageal, head and neck, liver, lung, prostate, and pancreatic cancers
Why performed: Proton beam therapy, like traditional radiation therapy, is performed to kill cancer cells. It may be performed as a primary treatment for a tumor, to kill any cancer cells that remain after surgical cancer treatment, or in addition to other cancer treatment options. Proton beam therapy is offered at forty-five locations in the United States. While for many cancers it was once considered an experimental treatment, in the 2020s, it is considered a well-studied and accepted form of cancer treatment.
Proton beam therapy is a site-specific therapy, so it is designed to treat solid tumors and cancers that have not spread to large areas or throughout the body. It is used to treat many kinds of cancer, including brain, breast, eye, esophageal, head and neck, liver, lung, prostate, and pancreatic cancers.
Patient preparation: The patient should discuss with the cancer care team any necessary preparation for the specific procedure that they are undergoing. Necessary preparation may vary depending on the type of cancer being treated and the patient’s previous response to any radiation therapy.
Steps of the procedure: Proton beam therapy uses high-speed protons to kill cancer cells instead of the electrons used by most radiation therapy techniques. Atoms comprise a nucleus of protons and neutrons surrounded by orbiting electrons. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. When free protons come very close to an atom, the electrons orbiting the nucleus are attracted to the positive charge of the protons. The electrons are then pulled out of their orbits. This is called the ionization of the atom. Atoms that have been ionized are not as stable as ordinary atoms. This change to the atom means that changes also occur to the molecule of which the atom is part and eventually to the cell of which the molecule is part. If the cell cannot repair the damage caused, then it ultimately dies.
Proton beam therapy begins with protons traveling around a synchrotron, a machine that makes the protons go very fast and energizes them. The protons are then sent through vacuum tubes to the machine that aims them at the area of the patient that will receive the radiation. The patient is positioned and held still so the proton beam can be aimed as accurately as possible. Complex computer technology helps doctors and technicians aim the proton beam very accurately so that it hits as little healthy tissue as possible.
The protons are released in a directed stream toward the cancer cells. The protons are traveling very quickly at first, but they slow down as they get closer to the cancer. When they travel fast, they do not have a powerful effect on the atoms they pass. When they are slower, however, they have a powerful effect. This is one reason that proton beam therapy causes less damage to healthy cells than traditional radiation therapy. Conventional radiation therapy uses X-rays, which strongly affect all the cells with which they come into contact, which makes it hard to deliver enough radiation to the cancer cells without also killing healthy cells. With proton beam therapy, doctors aided by computers can determine the right way to release the protons to have the maximum impact just as they come into contact with the cancer cells. Proton beam therapy may need to be repeated one or more times, depending on the size and type of the cancer and other factors.
After the procedure: After proton beam therapy, many individuals experience no negative side effects. Some individuals, however, may experience pain, fatigue, nausea, or diarrhea.
Risks: For most people, the risks associated with proton beam therapy are lower than those associated with traditional radiation therapy. This is the case because proton beam therapy causes less damage to surrounding healthy cells, so healthy tissue is less likely to be significantly damaged. Some of the risks of proton beam therapy include nausea, diarrhea, and fatigue. Damage to healthy tissue is still a possible risk of proton beam therapy.
Results: The goal of proton beam therapy is to destroy a tumor, to reduce the size of a tumor, to reduce related symptoms, or to kill any residual cancer cells left after a tumor has been surgically removed. Success rates for proton beam therapy can vary drastically depending on the type of cancer, its size, and how far it has spread. It has been found to be successful at reducing the side effects usually associated with traditional radiation therapy. If the procedure is done to completely destroy a tumor or residual cancer, then the procedure is generally considered to have been successful if the cancer does not return for five years or more. If the procedure was done to reduce tumor size, it is considered successful if the is improved. While proton beam therapy was once considered investigational and niche, it is now a well-known and widespread cancer treatment. However, proton beam therapy is not without controversy or detractors and remains under study in the 2020s.
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