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What Is Radiation Therapy for Malignant Mesothelioma?
Radiation therapy is used to extend survival and relieve pain for people with mesothelioma.
It uses ionizing radiation, which are high-energy X-rays or particles, to damage the DNA of cancerous cells and kill them. This results in tumor shrinkage as well as prevention of cancer recurrence and spreading.
Radiation is a focused treatment, so it only has effects on the parts of the body where it is directed. It is not painful during administration. There’s no need to worry about pain when a radiation oncologist delivers this mesothelioma treatment. After treatment, some people may experience skin irritation around the area where radiation was delivered.
Radiation oncologists offer this therapy to patients in different stages of mesothelioma for a variety of benefits.
Benefits of Radiation Therapy for Mesothelioma
- Improved Survival: When combined with surgery and chemotherapy, radiation helps some patients live longer by reducing the risk of local recurrence. Some patients may live three to five years longer with this multimodal approach.
- Pain Relief: Radiation therapy alleviates pain by reducing the size of mesothelioma tumors. This relieves pressure on the lungs, chest or spine. Approximately 60% of mesothelioma patients report symptom relief after radiation therapy.
- Seeding Prevention: During surgery, microscopic cancer cells can move to new areas. This is known as seeding. Radiation therapy along incision sites is relatively common, although recent studies have questioned its effectiveness.
Radiation for Pleural Mesothelioma
A 2016 study from researchers at New York’s Icahn School of Medicine reviewed the outcomes for thousands of pleural mesothelioma patients. Overall survival at two and five years was nearly double for patients who received mesothelioma radiation therapy, regardless of what other treatments were used.
A 2020 study published in Lung Cancer reported longer overall survival among early-stage pleural mesothelioma patients who received radiation therapy in addition to surgery and chemotherapy. A significant survival benefit was not reported among patients in later stages.
In 2021, researchers concluded that prophylactic irradiation of tracts, areas affected by diagnostic or therapeutic procedures, significantly reduced the occurrence of metastasis for pleural mesothelioma patients who underwent chest wall procedures.
Types of Radiation for Mesothelioma
Radiation therapy for malignant mesothelioma can be applied externally and internally. The internal form of radiation therapy for mesothelioma is called brachytherapy. The external form of radiation therapy is called external beam radiation therapy (EBRT).
EBRT is more commonly used for pleural mesothelioma because it has proven more effective.
External Beam Radiation Therapy
External beam radiation is a noninvasive radiation therapy procedure, and it involves high-energy rays aimed directly at malignant tumors.
The most common and effective type of EBRT for mesothelioma is intensity-modulated radiation therapy. IMRT is an advanced form of three-dimensional conformal radiation therapy. It changes the strength of beams in certain areas, allowing it to precisely target tumors.
The radiation beam conforms to the 3D shape of the tumor and is emitted in multiple doses. This permits higher radiation doses within the tumor, while minimizing the dose to the surrounding organs and tissues.
A 4D version called image-guided radiation therapy offers a CT scanner and radiation therapy in one machine, allowing patients to stay in one room for imaging and delivery of radiation.
A new type of ERBT called proton therapy uses a beam of protons – instead of photons – to more precisely target mesothelioma tumors. This type of radiation is only available at certain cancer centers throughout the U.S.
External beam radiation is fast and painless, and each radiation therapy session takes only a few minutes. Setup time — getting you in the right position for treatment — can take longer. Radiation oncologists usually offer treatments five days a week for several weeks.
Brachytherapy is a type of radiation therapy that kills cancer cells with a radioactive material implanted in the tumor.
Doctors may place the radioactive material during surgery or using a hollow tube with the aid of an imaging scan. Brachytherapy may also be applied temporarily to biopsy and surgical scars to prevent cancer from spreading.
It has been effective in treating lung cancer when placed into a tumor site, but it is seldom used for the treatment of mesothelioma.
Side Effects of Radiation Therapy
- Skin problems
- Hair loss near the radiated area
- Difficulty swallowing
- Shortness of breath
- Cough, fever and fullness of the chest (radiation pneumonitis)
- Scarring of the lungs (radiation fibrosis)
Side effects of mesothelioma radiation are most often temporary and are typically more constrained than those of chemotherapy, which can affect the entire body. However, some side effects of radiation may be chronic and appear months or years after the patient finishes treatment, including a low risk of secondary cancer.
Radiation-related skin irritation, known as radiodermatitis, is most common at the point where the radiation beam was focused. It can cause rashes, redness and a tight feeling or swelling. Peeling or darkening of the skin may occur.
Loss of energy is typically most severe two to four hours after a radiation session. It may also peak between the third and fifth week of treatment as the healing process uses more of the patient’s energy.
Radiation Side Effects by Mesothelioma Type
Receiving radiation to the chest could temporarily intensify symptoms of pleural mesothelioma such as shortness of breath, difficulty swallowing and coughing.
In rare cases, scarring of the lungs, called fibrosis, may occur.
Radiation to the chest can also cause inflammation to the linings of the heart or the lungs (radiation pneumonitis). There is also a risk of damage to the heart muscle, resulting in cardiac toxicity.
Other rare complications of radiation therapy for mesothelioma include fluid buildup (pleural effusions), collapsed lungs and calcification of the lymph nodes. Research shows that pleural effusions, if they develop at all, are typically reported within six months of the initial mesothelioma radiation treatment.
“If you’re not a candidate for surgery, radiotherapy can do almost as well as surgery. And the combination of the two is even better, like 40% better, and that’s significant.”Dr. Emanuela TaioliEpidemiologist at Mount Sinai Hospital in New York City
Radiation therapy has limited usefulness for those with peritoneal mesothelioma. The reason is location.
Peritoneal cancer involves the lining of the abdominal cavity. Radiation can be extremely toxic to the small intestines, liver, kidneys and other organs in this area. Nausea, vomiting and inflammation in the bladder are the most common side effects in patients who receive radiation to the abdomen.
The only kind of radiation used on peritoneal patients is to prevent cancer spreading to biopsy and surgical scars.
Radiation in Multimodal Therapy
When combined with surgery for pleural mesothelioma, EBRT can be applied after, before or during the procedure. Appling radiation therapy at different times produces different effects.
Radiation Therapy After Surgery
Traditionally, multimodal therapy for pleural mesothelioma begins with chemotherapy followed by surgery and then radiation therapy once the patient recovers from surgery.
- In this setting, radiation is used to kill cancer cells left behind in surgery. This technique delays or reduces the risk of local recurrence.
- About half of early-stage patients with epithelioid mesothelioma can live longer than five years with this multimodal treatment.
Surgery for Mesothelioma After Radiation Therapy (SMART)
This approach to treatment is a reversal of the traditional protocol. It has produced impressive results for some mesothelioma patients.
- In a 2015 study, specialists at two leading cancer centers in Toronto estimated a median overall survival of 51 months for pleural mesothelioma patients using the SMART approach. Around 66% of patients with early-stage epithelioid tumors lived longer than three years.
- It takes an experienced multidisciplinary team to safely execute the SMART approach. A high level of radiation is applied to the lung, which could be fatal if the lung isn’t subsequently removed. This means that once a patient receives radiation, they must follow through with surgery.
Intraoperative Radiation Therapy
Intraoperative radiation therapy (IORT) is used as part of a surgical procedure.
- A radiation oncologist applies the beams to the affected areas to help prevent any seeding or spreading of the cancer cells during the operation. A concentrated dose of radiation is delivered to the tumor site immediately after the tumor is removed.
- This option may help some patients finish treatment sooner, reducing the need for additional radiation therapy following surgery. Patients who require additional radiation sessions can get a boost from IORT and typically experience fewer complications.
Radiation Therapy Process
Most people are not sure what to expect when receiving radiation therapy. In general, patients go through an initial consultation, get imaging scans, and then receive treatment on an outpatient basis.
- First Appointment: During the consultation visit, you will meet with a radiation oncologist to discuss the best approach for your case. You might be asked to sign a consent form once you are fully informed of the process and want to proceed with treatment.
- Imaging Scans: To ensure accurate and safe application, imaging scans are performed to determine the exact size, shape and location of tumors. The application of radiation is based on these images to ensure safety.
- Treatment: A medical professional will explain what you need to do before, during and after treatment. They will help position you and apply protective coverings to prevent radiation exposure to healthy tissue. Radiation is typically applied one or more times a week for several weeks.
- Follow-Up Appointment: During follow-up appointments, your doctor will check you for signs of side effects. Imaging scans will be taken to keep a close watch on how radiation affected the size of your tumors.
Is Radiation Therapy Right for You?
Despite recent advances, a number of experts question the merits of radiation therapy for mesothelioma. These concerns arise from the inconsistent results published in clinical trials and scientific studies.
The decision to include radiation therapy in your treatment plan is up to you and your oncologist. The potential benefits of the therapy might outweigh the risks and side effects.
However, you need to discuss the pros and cons with your oncologist to make an informed decision.