What is Radiation Therapy?
This type of treatment used for various types of cancer, not just mesothelioma, uses high-energy beams of radiation to kill cancer cells. The radiation may be X-rays or gamma rays, as well as high-energy, charged particles. These high-energy particles and rays kill living cells by damaging the DNA, the genetic material.
When DNA is damaged badly enough, a cell will stop growing and dividing. The dead cell is then broken down and recycled or eliminated from the body through natural processes.
Radiation kills all cells, not just cancer cells. Technicians and oncologists administer radiation in a way that is targeted to minimize the death of healthy cells and minimize side effects.
Types of Radiation Therapy
Radiation therapy can be used in two main ways: externally and internally, depending on how it is applied to the patient. There are more specific variations within these two categories.
External Radiation Therapy
External radiation involves using a machine that creates a beam of radiation and aiming that beam at the part of the body in which cancer has been found. The actual procedure is painless and is a lot like getting an X-ray. There are several different variations on external radiation therapy.
One of these variations is image-guided radiation therapy, which uses CT scans or MRI images to target the tumor in the body and aim the radiation beam more accurately. Three-dimensional radiation uses these images but pieces them together to give an even clearer picture of where the tumor is. Using images helps to minimize the exposure of healthy tissue to radiation.
Another type of externally applied radiation is known as intensity-modulated radiation. It is administered in varying bursts of intensity. This allows the treatment to better target the exact size and shape of the tumor, again minimizing harm to healthy cells and resulting side effects.
Systemic Radiation Therapy
Systemic radiation therapy is a different way of targeting tumor cells with radiation. Instead of using an external beam, radioactive drugs are used to deliver radiation systemically throughout the whole body. This is an internally administered type of radiation.
The drugs can be given intravenously or orally. The radioactive drug is typically attached to an antibody that targets cancer cells so that the radiation is not delivered to all cells in the body. The radioactive material accumulates in the tumor, where it can kill cancer cells.
Brachytherapy is another type of internally delivered radiation therapy used to treat mesothelioma and other types of cancer. A radioactive substance is placed within an implant, which is then surgically placed inside the body, next to the tumor.
Here the material will emit radiation to kill cancer cells. The benefit of this type of radiation therapy is that, although it is invasive, it allows for a higher dose of radiation to be targeted at a smaller area of the body.
Brachytherapy implants may be placed permanently, which is called seeding or seed implantation, or temporarily. The radioactivity, or the radiation emitted by the material in the implant, diminishes over time, so permanent placement does not mean that a patient will have a device emitting radiation inside of them forever.
Curative Mesothelioma Radiation Therapy
There are two possible goals in using radiation therapy in patients with mesothelioma. One is as part of an overall treatment plan that is hoped will be curative.
For people diagnosed in an early stage of mesothelioma, a cure is considered unlikely but not impossible before the cancer has spread very far from the pleura or peritoneum. Aggressive treatment that includes radiation gives these patients a chance at eliminating the cancer or going into remission.
The most common way that radiation is used in mesothelioma is after surgery. Surgery is the best way to attempt to cure early-stage mesothelioma. It is used to remove as much of the cancer as possible. After surgery, radiation is used to destroy any remaining cancer cells and reduce the risk of cancer returning.
Mesothelioma cancer cells are particularly sensitive to radiation, but using this as the lone treatment is not usually possible because the nearby organs—the lungs, heart, and spinal cord—are also sensitive to radiation.
Doses of radiation high enough to cure mesothelioma without the aid of surgery would cause too much damage to these other tissues.
Even when a multi-modal treatment approach that includes radiation cannot cure mesothelioma, it is often successful at extending the life expectancy of early-stage patients. One study showed that life could be extended by nearly three years in patients who underwent radical surgery followed by high doses of radiotherapy.
Surgery After Radiation Therapy
SMART consists of administering radiation therapy after surgery, which is said to help with side effects. Following surgery, studies suggest that the patient will be able to tolerate powerful radiation treatment more effectively.
According to the Journal of Thoracic Oncology, patients will generally undergo Intensity Modulated Radiation Therapy (IMRT), before surgery. Undergoing radiation first can help physicians remove more cancerous tumors, and, in turn, patients could have a higher chance of successful surgery.
“This innovative protocol presents encouraging results and supports future studies looking at long-term outcome in patients with epithelial subtypes,” NCBI reports.
Radiation Therapy for Palliative Care
The other reason to use radiation therapy for mesothelioma patients is to relieve pain or reduce other cancer symptoms by shrinking the size of tumors. Radiation therapy has been shown in research to reduce the pain of patients with pleural mesothelioma.
By reducing the size of the tumor, pressure on the lungs and pleura is reduced. In other types of mesothelioma, radiation can have a similar palliative effect. Even when there is no hope for a cure, radiation can still be a useful treatment.
Side Effects of Radiation Therapy
Because radiation therapy is usually targeted, side effects are typically not as severe as with other treatments like chemotherapy. The targeting is not perfect, though. For instance, an external radiation beam has to go through the skin, which means that skin-related side effects are common. These include:
- Hair loss and extended dryness
Another possible side effect of radiation therapy is fatigue, which mostly sets in after a couple of weeks of radiation treatments. Other potential side effects include low white blood cell and platelet counts, which can cause infections and bleeding. Eating difficulties are also common, especially with radiation therapy for peritoneal mesothelioma.
With radiation therapy, there is also a risk that the radiation will cause long-term damage to organs near the tumor site. With mesothelioma, this especially puts the lungs and heart at risk.
There is also a possibility that radiation treatment will increase the risk of developing another type of cancer. With mesothelioma, though, a patient’s life expectancy is already limited, so this is not often a concern.
Weighing Benefits and Risks
The idea of getting radiation therapy can be overwhelming, considering the potential risks and side effects. As with any medical treatment, it is important to weigh the benefits against the risks. Benefits include:
- Potentially curing the cancer
- Extending life expectancy
- Reducing pain
Risks of radiation therapy include:
- Feeling fatigued
- Getting infections
- Developing another type of cancer
If you have been diagnosed with mesothelioma, consider the benefits and risks of radiation and take into account the advice and expertise of your medical team as you make final decisions about treatment.
Rely on the support of your loved ones as well to help you make difficult choices. Considering how aggressive mesothelioma is, radiation as an aggressive treatment makes sense for most patients despite side effects.
According to a report published by the U.S. National Institutes of Health, treating mesothelioma with radiation therapy is challenging, especially if it’s the only form of treatment. In turn, multi-modal therapy is almost always an option, meaning radiation therapy is combined with other forms of treatment. According to the study, combining treatments improves prognosis.
“No consensus exists with regard to the use of RT as a standard treatment modality in mesothelioma,” the study said. “A retrospective review of 663 patients from three institutions demonstrated an improvement in overall survival with the use of multi-modality therapy versus surgery alone.”
With multi-modal treatment, some mesothelioma patients have extended the typical life expectancy of someone with the disease from 32% to 55%.
Page Medically Reviewed and Edited byLuis Argote-Greene, M.D.
Luis Argote-Greene is an internationally recognized thoracic surgeon. He has trained and worked with some of the most prominently known thoracic surgeons in the United States and Mexico, including pioneering mesothelioma surgeon Dr. David Sugarbaker. He is professionally affiliated with University Hospitals (UH). His areas of interest and expertise are mesothelioma, mediastinal tumors, thoracic malignancies, lung cancer, lung transplantation, esophageal cancer, experimental surgery, and lung volume reduction. Dr. Argote-Greene has also done pioneering work with video-assisted thoracoscopic surgery (VATS), as well as robotic assisted minimally invasive surgery. He has taught the procedures to other surgeons both nationally and internationally.