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Proton therapy is a treatment strategy similar to external beam radiation. However, this treatment uses protons rather than high-energy photons. There are several reasons to choose proton therapy over other types of radiation. For example, proton therapy better targets the tumor and cases less damage to surrounding healthy tissue.
Certain types of cancer are more often targeted with proton therapy, including head and neck, eye, brain, prostate, and lung cancer. Mesothelioma patients may also benefit from proton therapy, although there are limitations depending on the stage of the disease. This is a newer treatment, and while it shows great promise, researchers continue to refine the technique.
What is Proton Therapy?
Proton therapy, also called proton beam therapy, is a type of radiation used to treat patients with certain types of cancer. It is an external beam therapy, meaning a machine generates a beam of radiation. This beam is aimed at the patient’s body, penetrates skin and other tissue, and ultimately hits the tumor to kill cancer cells.
Protons are charged particles at the centers of atoms. When protons are targeted at living cancer cells, they ionize the molecules in those cells. The ionization damages the cells’ genetic material. Healthy cells usually recover from this damage, but cancer cells are more vulnerable, usually dying after the damage is done.
Protons from an external beam can be given a specific amount of energy. This energy affects the speed and distance they travel inside the body. By giving the protons calculated amounts of energy, the machine precisely directs the beam to the tumor, ensuring it will not penetrate into healthy tissue.
An Alternative to Standard Radiation
Other types of radiation therapy use particles called photons. Photons make up high-energy radiation like X-rays and gamma rays. These rays are effective at killing cancer cells but also damage healthy cells and are more difficult to control. Unlike protons, photons cannot be given a specific amount of energy. This makes controlling them much more difficult.
As radiation from X-rays or gamma rays enter the body, it penetrates and damages tissue on the way in, in the tumor, and on the other side. Essentially, traditional radiation therapy is consideraby more damaging to healthy tissue than proton therapy is. Because proton therapy gives doctors greater control of where to deposit the damaging radiation, they can also give a higher dose of radiation to the tumor than is possible with traditional radiation therapy.
Treatment for Mesothelioma
Treatment with proton therapy is very specific to a tumor. This specificity is beneficial for patients with one or two tumors. Therefore, patients whose cancer has metastasized to form multiple tumors, this treatment is relatively ineffective. Patients with multiple tumors benefit more from systemic chemotherapy, which circulates drugs through the entire body to destroy cancer cells.
Proton therapy may be used to treat mesothelioma, depending on how far the cancer has spread. Unfortunately for many mesothelioma patients, a diagnosis comes when the cancer is in the later stages and metastasis has already occurred. These patients are not good candidates for proton therapy. However, those patients whose pleural mesothelioma has not spread beyond the chest cavity, proton therapy may be a good choice for shrinking tumors while avoiding damage to vital organs nearby.
Treatment for Lung Cancer
Patients with asbestos-related lung cancer are often good candidates for proton therapy. Research has found that this treatment can be more safe and effective than traditional radiation therapy. For example, one study showed lung cancer patients undergoing proton therapy were less likely to develop serious side effects than those receiving traditional radiation therapies.
Radiation therapy to the chest cavity comes with the risk of some serious complications. Potential complications include pneumonitis and esophagitis. These conditions are inflammation of the lungs and esophagus, which both cause serious, often permanent symptoms. Studies of proton therapy on lung cancer patients showed significantly reduced side effects.
What to Expect
If you will be receiving proton therapy for mesothelioma or lung cancer, you should know what to expect. First, you will meet with the medical team that will administer treatment. Members of the team will examine you and give you opportunity to ask questions.
Next, you will be given a simulation that precedes treatment. The simulation is a planning session for the medical team. They will create molds and masks to help you stay in position during the actual treatment. These devices make it easier to remain still and in the proper position to minimize potential damage. Your skin will also be marked so the correct area is targeted during treatment. During simulation, you may also undergo imaging scans with a CT scanner, PET scanner, or MRI to help guide the treatment.
For the actual treatment, the team will position your with the molds and other devices used to help you stay securely in place. The proton beam is then aimed at the proper place on your skin. Although the medical team must leave the room during treatment, they will monitor treatment through computers. The actual treatment is painless and takes between 30 and 90 minutes. Most patients experience multiple treatment sessions, up to once daily for eight weeks.
Potential Side Effects
Although side effects and complications are greatly minimized with proton therapy, there are still potential side effects. Proton therapy poses a lower risk to healthy tissue because of the control doctors have over the radiation. However, some possible side effects are irritation, redness, hair loss, or swelling at the area targeted by the beam.
Proton therapy is an exciting development in cancer treatment. Many people struggling with asbestos-related cancers may benefit from this innovative therapy. With targeted radiation to the tumor, higher doses, and minimized healthy tissue damage, proton therapy is shrinking tumors more effectively and with fewer side effects.
Page Medically Reviewed and Edited by Anne Courtney, AOCNP, DNP
Anne Courtney has a Doctor of Nursing Practice degree and is an Advanced Oncology Certified Nurse Practitioner. She has years of oncology experience working with patients with malignant mesothelioma, as well as other types of cancer. Dr. Courtney currently works at University of Texas LIVESTRONG Cancer Institutes.