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.
Intraoperative Radiation Therapy
Like brachytherapy, intraoperative radiation therapy is delivered internally. While performing a surgical procedure, doctors administer radiation therapy directly to the cancer site.
This is a beneficial strategy for patients with tumors that surgeons cannot remove easily or completely. The direct radiation allows for a more intensive dose than could otherwise be safely achieved.
How Is Radiation Therapy Used to Treat Mesothelioma?
Radiation is not typically a curative treatment or a treatment used in isolation. Most commonly, doctors turn to this therapy to reduce tumor size, relieve symptoms, and as an adjunct to other treatments.
As Part of Multimodal Treatment
Treatment teams most commonly choose radiation as part of a multimodal treatment plan. This may include combining it with surgery, with chemotherapy, or with both.
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.
Radiation can also reduce the risk of seeding after surgery. Seeding occurs when cancer cells spread along the incision site during surgery.
Radiation as Part of Curative Treatment
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.
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 multimodal 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 – The SMART Protocol
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 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,” the study reports.
One study found that patients undergoing the SMART protocol had a median overall survival time of 51 months. This is a major improvement compared to many other treatments.
Despite these results, not all experts agree that SMART is a good treatment option. A recent study conducted at the Mayo Clinic indicated that treatment-related morbidity was a real issue.
This is due to the fact that the SMART protocol uses extrapleural pneumonectomy (EPP) as the surgical procedure. EPP is a radical surgery with high fatality rates compared to other treatments. The Mayo Clinic researchers concluded that SMART was not appropriate for most patients.
Combining Radiation Therapy with Immunotherapy
A new area of research for radiation therapy is in combination with immunotherapy. Studies and clinical trials have found some promising results when using checkpoint inhibitors in mesothelioma patients. These immunotherapy drugs help the immune system recognize and attack cancer cells.
Most recently, there is some evidence that radiation therapy could enhance the effects of immunotherapy drugs. Radiation’s antitumor effects may stimulate the immune system. Researchers hope to continue studying this treatment strategy in clinical trials.
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.
What Are the Official Guidelines for Treating Mesothelioma with Radiation?
The National Comprehensive Cancer Network (NCCN) and similar organizations create official guidelines for mesothelioma treatment based on research. The NCCN and other guidelines include several points on using radiation therapy:
- Radiation therapy can be used as part of multimodal treatment but is not recommended as stand-alone therapy.
- The NCCN does not recommend radiation as an adjuvant to surgery to prevent seeding except in some cases and in clinical trials.
- Radiation therapy is useful for palliation to relieve symptoms, including chest pain and obstructions in the esophagus or bronchial tubes. It can also provide relief from metastasis to the brain or bones.
- Another professional organization recommended in 2019 that radiation therapy be used before or after extrapleural pneumonectomy, such as in the SMART protocol, as an adjuvant to less radical surgeries, and as palliative 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:
- Extending life expectancy
- Reducing pain
- Alternative to surgery
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.
Does Radiation Therapy Improve Survival Time?
A common goal of treatment for mesothelioma patients is to extend life expectancy. For most patients, a cure isn’t possible, but the right treatment plan can help them live longer more comfortably.
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, multimodal 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 multimodal treatment, some mesothelioma patients have extended the typical life expectancy of someone with the disease from 32% to 55%.
How to Prepare for Radiation Therapy
When undergoing radiation therapy for the first time, it’s best to know what to expect. Your medical team will describe what you need to do to prepare and what to expect. For standard, external radiation therapy, expect the following steps in preparation:
- Imaging scans. Radiation oncologists will take CT scans of your body to create the best strategy for targeting tumors with the radiation beam.
- Simulation. The radiation team will also prepare you by simulating the procedure before actually doing it. They will move you around to find the best position for accurate targeting of the tumors and to keep you comfortable. It is essential that you remain still during the treatment.
- Dosing and radiation type. Finally, your treatment team will use all this information to determine the type of radiation you will receive and the best does.
External beam radiation can be a little uncomfortable because the radiation oncologist and technicians need to manipulate your body to the right position, which you then need to hold. It is not, however, painful.
As you lie in position, the radiation machine moves around your body, targeting the predetermined locations. The entire process may take up to 30 minutes, but the actual radiation treatment is only a few minutes. You may need to hold your breath for short periods of time.
Radiation therapy is an important component of mesothelioma treatment for many patients. If you have questions about proceeding with this therapy, talk to your medical team and share your concerns.
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.