What Is Radiation Therapy for Mesothelioma?
Radiation therapy, also called RT, is the delivery of targeted energy to treat or control mesothelioma tumors. It can help control pain in people with mesothelioma.
Although it is not a cure, recent studies show modern, precise forms of radiation therapy can improve prognosis and prolong survival in patients with pleural mesothelioma. Radiation therapy may be used alone or as part of a multimodal treatment plan.
How Is Mesothelioma Radiation Therapy Used?
Pleural tumors can invade the chest wall and become painful as they grow. Radiation can be used to shrink these tumors and lessen pain.
Following surgery, radiation therapy can be used to enhance the effectiveness of the overall mesothelioma treatment plan — and helps doctors kill remaining tumor cells.
The current roles of radiation therapy in pleural mesothelioma treatment include:
- Palliative pain relief
- Supportive therapy after surgery
- Prevention of seeding
Seeding is the unintended spread of cancer cells to nearby tissues or surgical incisions during biopsies, insertion of medical devices or mesothelioma surgery.
Who Delivers Radiation Therapy?
A mesothelioma specialist known as a radiologist applies ionizing radiation to the tumor area.
The treatments are not painful, although the skin can have a “sunburned” feeling after several treatment sessions.
How Does Radiation Work?
Radiation therapy works by damaging the genetic material, or DNA, necessary for cancer cell growth and replication. It can damage normal tissue around the cancer treatment area, but modern radiation is very precise and minimizes damage to healthy tissue.
The benefit of radiation therapy for pleural mesothelioma is it does not cause intense, systemic side effects associated with chemotherapy such as severe nausea, mouth sores and low blood cell counts.
Types of Radiation for Pleural Mesothelioma
Radiologists use two forms of radiation therapy to treat pleural mesothelioma: Brachytherapy and external beam radiation therapy.
Brachytherapy is less common and involves placing a source of radiation, called a radioactive implant, directly into tumor tissue. External beam radiation delivers tightly targeted beams of radiation from outside the body. It is administered in several treatments over days to weeks.
Brachytherapy is less common than other forms of radiation therapy but still may be used in select cases.
Researchers are studying the value of brachytherapy in mesothelioma clinical trials. The radioactive implant emits radiation over a small area and directly targets the tumor. This damages cancer cells and can lead to noticeable shrinking of the tumor.
The radioactive implant can be placed permanently or temporarily. Permanent placement is more common for pleural mesothelioma. The object will release radioactivity for only a few months in most cases.
Placement of Brachytherapy and Treatment Considerations
- Tiny seeds filled with radioactive material are placed directly into tumors with a needle or other medical device.
- Imaging may be used during and after placement to ensure the seeds are correctly placed inside the tumor.
- If you are traveling or attending high-security events, be aware the seeds can set off metal detectors, even after they stop emitting radiation.
- Permanent brachytherapy implants may set of radiation detectors for several weeks to months after placement.
- High-dose surface brachytherapy is temporary and places a radioactive source on the skin near the tumor.
- Surface radiation may be used to prevent tumor seeding along incisions following mesothelioma surgery.
- The length of temporary brachytherapy will vary by patient and may require an overnight hospital stay.
Both forms of brachytherapy are effective at killing cancerous cells but neither can cure pleural mesothelioma. Brachytherapy often is used in conjunction with other treatments.
External Beam Radiation Therapy
External beam radiation therapy, also referred to as EBRT, delivers radiation externally, from a machine using a radioactive beam. The treatment itself is painless but may cause skin irritation that feels like a sunburn.
Pleural Mesothelioma External Beam Radiation Therapy Steps
- Initial consultation: Patients learn about the procedure, how it is performed and what they’ll need to do to prepare and recover.
- Informed consent: Patients sign an informed consent document acknowledging the inherent risks of radiation therapy.
- Radiation simulation: An imaging simulation appointment helps determine patient body position for future treatments. It ensures the radiologist can plan accurate treatment. Props may be used to plan for your comfort and helping you stay motionless for treatments.
- Radiation tattoos: Small, usually semi-permanent markers, sometimes called radiation tattoos, are placed on the patient’s during simulation. Occasionally, the tattoos are permanent.
- During treatment: The treatment itself is painless. Patients may hear the machine making sounds during treatment or see the beam applicator moving. Most of the appointment is spent on proper patient positioning. Beams of radiation typically are administered for only a few minutes each session.
- Appointment duration and frequency: Appointments last about an hour. Therapy is most often given once or twice a day, five days a week for several weeks.
There are two types of external beam radiation. The difference lies in the radiation intensity and variation of intensity over the treatment area.
Three-Dimensional Conformal Radiation Therapy
Detailed imaging scans help radiologists tailor the radiation dose in three-dimensional conformal radiation therapy (3D-CRT). After collecting 3D images of pleural tumors, a customized plan is devised to deliver radiation using fixed beams.
The intensity of the radiation beam is uniform across the treatment area. Careful planning with the help of detailed tumor mapping minimizes the amount of radiation delivered to nearby, healthy tissue.
Intensity-Modulated Radiation Therapy
Much like 3D-CRT, intensity-modulated radiation therapy (IMRT) uses 3D images of pleural tumors to deliver radiation precisely. IMRT is different because the radiation intensity is modulated — or controlled — to administer varying levels of radiation across the targeted area.
Higher-intensity radiation can be delivered directly to the tumor with minimal harm to nearby healthy tissue.
Supportive Therapy After Surgery
Expert opinion on the value of post-operative pleural mesothelioma radiation therapy varies from doctor to doctor because some surgical procedures have lasting effects on the ability to administer the treatment.
For example, an extrapleural pneumonectomy removes the entire lung. Aggressive radiation therapy can be delivered to the area from which the lung was removed without endangering the health of the remaining lung.
But aggressive radiation following a pleurectomy/decortication (P/D), a surgery that preserves the affected lung, may not be feasible.
If radiation is delivered after P/D, the treatment requires more precision. The amount of radiation required to effectively treat tumors can be damaging to healthy lung tissue.
Advances in Radiation Therapy
Radiation oncologists must balance these two factors to provide effective and safe radiation therapy.
A newer form of RT called intensity-modulated radiation therapy (IMRT) can safely administer high doses of radiation following a pleurectomy/decortication.
If the patient is a candidate for IMRT, it may be used in conjunction with P/D to improve survival time and quality of life.
Preventing Mesothelioma Tumor Seeding
Pleural mesothelioma cells can spread along the insertion line for thoracentesis, biopsies, chest tube sites and surgical incisions.
Once the cancerous cells adhere to these new areas in a process known as seeding, they can form small tumors called nodules. Seeding is estimated to occur in 20% to 50% of mesothelioma patients who undergo such procedures.
In an attempt to prevent spreading, doctors can irradiate the incision and drainage sites with prophylactic radiation therapy in the weeks following the procedures.
Expert opinion on the benefits of radiation therapy to prevent seeding are mixed: Some studies show radiation therapy won’t prevent all cases of seeding but may reduce the risk.
Recommendation 1.1 of the 2018 Treatment of Malignant Pleural Mesothelioma: American Society of Clinical Oncology Practice Guideline states, “Prophylactic irradiation of intervention tracts should generally not be offered patients to prevent tract recurrences.
The quality of the evidence supporting this recommendation is rated as “high,” but the strength of the recommendation is “moderate.”
This moderate rating indicates some physicians still may choose to offer prophylactic radiation therapy to minimize the risk of seeding.
If you have questions about this type of radiation therapy, talk to your doctor about the risks and benefits for using it to prevent seeding in your situation.
Palliative Pain Relief
Radiation therapy can lessen pain for patients with tumors growing into the chest wall or lymph nodes, according to the European Respiratory Society and the European Society of Thoracic Surgeons.
While radiation therapy won’t relieve all sources of pleural mesothelioma pain, research suggests it is effective for managing:
- Shortness of breath (dyspnea)
- Pancoast’s syndrome — pain in the shoulder, arm and hand
- Superior vena cava obstruction
Short courses of radiation therapy are used to decrease pain and improve quality of life.
Longer radiation therapy treatment plans are undertaken to aggressively treat the disease and aim for disease remission.
Mesothelioma doctors can use radiation therapy for pain relief and as part of a “chronic illness” management plan. With this approach, doctors don’t expect to eradicate the cancer completely. Instead, they treat it as a chronic condition and buy patients more time and better quality of life.
For example, pleural mesothelioma survivor Judy Glezinski had surgeries in 1990 and 1997 to remove tumors from around her lungs. Several years after her last surgery, doctors used radiation therapy to treat a specific area that was causing Judy pain.
Judy was relatively pain-free for a full year after receiving radiation therapy.
What to Expect Before Mesothelioma Radiation Therapy?
Prior to treatment, patients receive instructions from a doctor or nurse on preparing for radiation therapy. Sometimes patients are asked to follow certain bowel and bladder preparation regimens so these areas are empty during treatment.
Imaging scans are taken before radiation is delivered. Computed tomography (CT) or magnetic resonance imaging (MRI) scans are commonly used for this.
In some cases, certain chemicals, called radiosensitizers, are used in combination with radiation therapy. This can make cancer cells more susceptible to radiation. Other chemicals, called radioprotectors can protect healthy cells from radiation damage.
Some radiochemicals are man-made drugs, such as the chemotherapy drug gemcitabine. It is used as a radiosensitizer.
A few natural substances, such as curcumin, a compound found in the Indian spice turmeric, can act as a radioprotector or a radiosensitizer, depending on dose and timing of use.
Side Effects of Radiation Therapy
Radiation therapy can cause early and late side effects. Early side effects occur during or right after treatment. The most common early side effects are fatigue and skin problems.
Skin around the area receiving radiation can:
- Become red and irritated
- Feel touch and sun sensitive
- Appear swollen
- Feel dry or itchy
- Peel or blister
Some people describe this side effect, called radiation dermatitis, as similar to a sunburn.
Late side effects typically occur months or years after radiation therapy is completed. Although much less common than early effects, late side effects often are permanent.
Lung tissue scarring or fibrosis may develop in the months or years following radiation therapy. Nearby lymph nodes may become calcified in some cases.
Other early and late side effects of radiation therapy for pleural mesothelioma include:
|Early Side Effects||Late Side Effects|
|Skin burns near application area||Radiation pneumonitis|
|Hair loss around treatment area||Pleural effusion|
|Feeling tired||Liver radiation damage|
|Esophagitis||Cardiac radiation damage|
Not everyone with pleural mesothelioma will experience the same side effects. The number and severity of side effects depend upon the dose and type of radiation received, as well as where it is applied to the body.
Though radiation therapy alone does not cure pleural mesothelioma, it can play a role in a multimodal treatment plan. Radiation therapy can reduce pain for people with pleural mesothelioma, and it may be used to prevent or treat tumor seeding.
Advances in radiology are improving radiation therapy options for people with pleural mesothelioma. These therapies are more accurate and effective against pleural mesothelioma tumors than ever before.
Impact of Nutritional & Alternative Therapies on Radiation Treatment
Tell your doctor if you are taking any nutritional therapies or dietary supplements.
This will help ensure any over-the-counter products you take don’t interfere with the intended cancer killing effects of pleural mesothelioma treatment.
To ensure you receive the most safe and effective cancer therapy, always tell your cancer care team if you are taking any other alternative therapies, too.