Radiation therapy is commonly used to treat pleural mesothelioma.
Patients may receive different types of radiation based on their individual case.
Radiation therapy is often used in combination with other cancer treatments.
Patients may undergo inpatient or outpatient procedures.
Radiation therapy is a common cancer treatment, including for mesothelioma. Patients may undergo radiation as part of a multimodal plan with chemotherapy and surgery, which has shown improved life expectancy for those with early-stage mesothelioma. Radiation therapy may also be used as a palliative treatment option to reduce symptoms and improve quality of life for patients with advanced disease.
Using Radiation as Mesothelioma Therapy
Mesothelioma radiation therapy may be used as part of a curative treatment plan or solely for palliative purposes. In general, radiation therapy techniques for mesothelioma patients commonly serve three purposes: seeding prevention, increasing patient survival rates, and managing discomfort.
Cancer “seeding” is a form of metastasis that occurs when microscopic cells are disturbed during surgery and spread elsewhere in the body. The use of radiation can kill the mesothelioma cells, preventing further tumor growth in previously healthy tissue. Preventing metastasis is imperative, as it accounts for approximately 90% of all cancer fatalities. One clinical trial showed that the use of radiation following invasive procedures in malignant pleural mesothelioma patients can reduce risk of “seeding” from 40% to 0% in some cases.
Radiation may also be used as a part of a multimodal, curative treatment plan with surgery and chemotherapy. Radiation therapy may be applied following these treatments to eliminate any remaining cancer cells in small, targeted areas of the body. In some cases, mesothelioma radiation may be administered during a surgical procedure, known as intraoperative radiation or IORT. This application of radiation therapy enables the rays to be delivered directly into the cancerous area of the body after the mesothelioma tumor has been removed. IORT makes it easier to administer the proper dosage and typically causes less harm to healthy tissue compared to other forms of radiation.
Radiation as a curative treatment is most often used for pleural mesothelioma patients, since the location of the tumors provides the lowest risk of damage to surrounding organs during treatment. Since pericardial mesothelioma develops in the heart and peritoneal mesothelioma develops in the abdominal cavity, radiation is infrequently applied because the surrounding organs can be easily damaged.
Clinical Success of Radiation Therapy in Mesothelioma Patients
According to a 2018 study looking at data from 2004 to 2013, malignant pleural mesothelioma patients treated with surgery plus radiation survived on average 21.4 months. Patients who underwent surgery alone lived an average of 16.6 months.
A similar study found radiation therapy combined with surgery and chemotherapy could improve survival for pleural mesothelioma patients. The patients that did not receive radiation had a two-year survival rate of 19.5% and a five-year survival rate of 5.3%. Patients who received radiation survived longer, with 33.9% surviving at least two years and 12.6% living five years or longer.
Often radiation therapy will not be recommended as a curative treatment for late-stage mesothelioma patients because the cancer has spread, but may be used for palliative care. Used in this way the therapy lessens severity of patient pain and improves quality of life.
Types of Radiation Therapy
Depending on an individual’s case, doctors may recommend various forms of radiation therapy. Historically, there have been two main forms of radiation therapy available to mesothelioma patients, external beam radiation and internal radiation. These two forms are most prevalent because of their ability to better target the cancerous cells and avoid healthy tissue compared to other forms of radiation, which also results in fewer symptoms.
External Beam Radiation
External beam radiation is the most common radiation therapy for mesothelioma patients. There are two types that can be used to treat the disease, both of which are typically administered as outpatient procedures.
Types of External Beam Radiation Therapy
- 3D-CRT uses 3D images and computer technology to ensure the beams of radiation match the size and shape of the tumor.
- The customization protects healthy cells and tissue during treatment, minimizing symptoms.
- The concentration of treatment solely on cancerous cells enables the use of higher radiation doses, which can more effectively kill the mesothelioma cancer cells.
- IMRT uses similar technology to control radiation dosage (large, dense tumors can receive a high dosage, while smaller tumors receive less intense radiation).
- The precision of IMRT protects healthy tissues and has fewer side effects than traditional external beam radiation.
- Helical tomotherapy (delivering the radiation in horizontal slices of the body) allows for the IMRT to be administered not only at varied intensities, but from different directions.
External beam radiation is typically used following surgery, like an extrapleural pneumonectomy. Patients undergoing external beam radiation experience fewer side effects because healthy cells have time to recover between treatment sessions. The therapy is given for a small period of time, typically less than a half hour for five successive days. Patients treated with external beam radiation are never radioactive. All radiation from the therapy stays in the treatment room, so it is not possible to transfer radiation to loved ones.
Studies have found that IMRT is more impactful for malignant mesothelioma patients than 3D-CRT. In a 2017 study, researchers were able to treat the targeted cancerous area 100% of the time using IMRT, as compared to only 71.29% of the time when using 3D-CRT. Additionally, IMRT has proven beneficial for pleural mesothelioma patients when surgery isn’t a viable option. Malignant pleural mesothelioma patients participating in a 2012 study receiving solely IMRT had a median overall survival of 17 months, compared to the average life expectancy of six months to about one year.
Brachytherapy is an internal radiation therapy often used for mesothelioma treatment plans that require higher doses of radiation. Radioactive material is implanted into the patient and allows for treatment inside, or very close to, the malignant tumor. The implants may be temporary or permanent based on treatment needs. Due to the high levels of radiation, brachytherapy is an inpatient procedure.
If a patient receives a permanent implant, their body will stop emitting radiation a few weeks or months after implantation. The care team will alert the patient if they need to change their daily activities to prevent loved ones from being exposed to radiation. For most adults there is little to no danger of radiation exposure from a brachytherapy patient, though pregnant women and small children may be impacted.
What to Expect During Radiation Therapy
Patients beginning radiation therapy will first meet with a radiation oncologist and radiation therapist who review medical records and x-rays, give a physical exam, and may recommend tests to ensure the therapy is the most beneficial option. If the patient is a candidate for radiation therapy, they will be referred to a mesothelioma treatment center. Patients are often given a simulation of the therapy first to better acquaint them with the process.
If receiving brachytherapy, the patient will get a tiny, temporary “tattoo” to denote where the implant should be inserted. During placement, a patient may undergo anesthesia to eliminate pain for the duration of the procedure. The implant may be temporary or permanent based on the patient’s needs.
External beam radiation treatments last about 15 minutes each session, and typically patients receive the therapy five times per week for up to nine weeks. A linear accelerator is used to administer the therapy and patients may hear a buzzing noise when it’s in operation. Both external beam radiation and brachytherapy should result in little to no discomfort during treatment.
Recovery and Side Effects from Mesothelioma Radiation Therapy
Unlike other cancer therapies, there is little to no recovery time needed after a course of radiation because side effects are limited. There are two waves of common side effects from the therapy, those initially felt after treatment and potential long-term effects.
Initial Side Effects
- Skin problems, akin to sunburn
- Hair loss at radiation site
- Dry mouth/Mouth Sores
- Decrease in white blood cells
Initial side effects may be worsened when radiation is coupled with chemotherapy.
The longer term radiation side effects may not manifest until months after treatment. These side effects in mesothelioma patients are directly related to the part of the body that receives the therapy. For instance, radiation of the chest may damage the lungs, increasing the appearance of symptoms related to pleural mesothelioma. These symptoms include shortness of breath and cough. Since abdominal radiation can damage internal organs, the therapy is less common among peritoneal mesothelioma patients to mitigate this risk.
While the above side effects are common, a patient’s body may react to the therapy in a variety of ways. Patients should discuss any side effects they’re experiencing with their healthcare team, who may be able to recommend lifestyle or dietary changes to help alleviate the symptoms.