Most aggressive mesothelioma treatments will involve some kind of radiation therapy. As a curative treatment (or a treatment employed to eliminate the disease and improve life spans), it is often used in conjunction with surgery and chemotherapy.
As a palliative treatment (or a treatment employed to reduce symptoms and improve quality of life), radiation therapy is often used on its own or with other palliative measures. Radiation therapy in general involves the use of ionized radiation to disrupt cancerous cell replication and decrease the size of tumors.
Mesothelioma radiation therapy can be used in a neoadjuvant, intraoperative, or adjuvant sense. As a neoadjuvant therapy, it is usually used prior to surgery to help shrink tumors or make them more malleable for easier surgical resection.
Intraoperative radiation therapies are applied during surgery so that the radiation has more direct access to tumors and cancer cell clusters. As an adjuvant therapy, radiation is applied to ward off remaining cancer cells after tumors have been removed by surgery.
There are generally three reasons why radiation therapy may be used:
- Pain relief – Radiation therapy reduces the size of tumors which can also reduce pain and other symptoms
- Preventing seeding – Surgeries can often displace cancer cells which can then start replicating and growing in new areas. Radiation therapy seeks to stop this “seeding”
- Improved lifespans – As a curative treatment, mesothelioma radiation can as much as double lifespans and survival rates
How Does Mesothelioma Radiation Treatment Work?
Radiation therapy has existed as a general cancer treatment for decades. Advancements over the years have made it an even more effective treatment for wide variety of cancers. In general, there are two types of mesothelioma radiation: external and internal.
As you might expect, external options are administered from outside of the body while internal ones are administered from inside the body. The most common form of radiation is external beam radiation, and internal radiation is rarely used for the treatment of mesothelioma.
Both types of radiation work in much the same way. The radiation damages the DNA of cancer cells which, in turn, disrupts the cells’ ability to replicate. This effectively kills cancer cells. It can also shrink tumors and make them more pliable for easier removal.
Radiation can also attack healthy cells, but most doctors try to avoid that as much as possible. They will use a combination of imaging scans such as X-rays, CT scans, and MRI images in order to find the best location to apply the beam of radiation. External radiation will almost always damage skin or muscle as it is impossible to avoid. Even so, specialists will try to limit the damage as much as they can.
External Mesothelioma Radiation
For the most part, patients who receive radiation treatment for mesothelioma are going to get some type of external beam radiation. It is the oldest type of radiation and the one most commonly used to treat mesothelioma.
As the name suggests, external beam radiation involves a beam of high-intensity radioactive waves from what’s known as a linear accelerator or linac machine being pointed at tumors or areas that have clusters of cancer cells.
The radiologist in charge of the procedure may place small dots on the patient’s skin to identify target locations. These dots may stay on for the duration of the treatment course (a few weeks).
The parts of the body that are not receiving radiation treatment will be shielded by a special covering. Patients will usually lay down on a table with the targeted area exposed. The radiologist sits in another room where they are usually assisted by a computer to help irradiate the target locations precisely.
The procedure itself is very short (usually only about 20 minutes) and can be done on an outpatient basis. There are, however, several rounds of radiation treatment that a patient might need to undergo. Generally, patients are asked to come in 4 or 5 times per week over the course of 3 or 4 weeks.
The amount of mesothelioma radiation therapy someone receives is based on all of the following:
- Size of the tumor
- Spread and stage of the disease
- Overall health
- Type of mesothelioma (pleural, peritoneal, or pericardial)
Mesothelioma is notoriously hard to treat with radiation partly because the tumors are located near major organs. For pleural mesothelioma which occurs in the lining of the lungs, organs at risk include the lungs, liver, and heart. For peritoneal mesothelioma which occurs in the lining of the abdominal cavity, vulnerable organs include the intestines, pancreas, and other abdominal organs.
While the procedure is being administered, tumors may shift position because of the patient’s breathing or because of the process of digestion. Because of this, several techniques are often used to assist the radiologist.
Image Guided Radiation Therapy
One such technique is known as image guided radiation therapy (IGRT). Radiologists use CT scanners to provide a real-time 3D video of the interior of the patient’s body. IGRT is considered to be 4D, however, with the fourth dimension being time. The method allows radiologists to account for movements in the tumor site’s positioning so that the radiation beam’s movement is synchronized.
The issue with IGRT is that many radiologists do not have the proficiency to offer this kind of treatment. Most hospitals also simply do not have the technology. Of course, the benefits are numerous. The likelihood of radiation damage occurring to major organs is greatly reduced.
Other healthy tissues also remain unaffected, a reality that standard beam radiation can’t promise.
Intensity Modulated Radiation Therapy
Intensity modulated radiation therapy (IMRT) is another type of external beam radiation. This particular method is often far more precise than standard beam radiation. Patients lie down in a cylindrical linear accelerator machine that shoots radioactive waves at the affected area from various different angles.
Another benefit of IMRT is the ability of the technology to modulate how intense the radiation is for each part of the body. It can provide a precise lock on the tumor site even if the site is near vital organs. The amount of radiation that makes it to healthy tissues is usually fairly negligible.
Of course, no treatment is entirely perfect, but this one offers the best technology available. Side effects associated with IMRT are far less compared to those of regular external beam radiation.
Three-Dimensional Conformal Radiation Therapy
Another form of external beam radiation is three-dimensional conformal radiation therapy (3D-CRT). It is similar to IMRT except that its radio waves are generally less intense. This procedure uses a combination of images from MRIs, CT scans, and PET scans to provide a 3D model of the tumor site. The beam of radiation is then conformed to the size and dimensions of the tumor.
3D-CRT is not quite as precise as IMRT, but still provides radiologists with more control over where the beam of radiation is located.
Proton therapy for mesothelioma uses an entirely different mechanism of radiation. While virtually every other method of external beam radiation uses photons (light waves), this form uses a beam of protons. This therapy allows doctor to control exactly how much radiation they use and how far they want the beam to go into the body. Radiation never has to extend past the tumor in question because the radiologist can program it to only go as far as the tumor site.
Another benefit is that more energy can be applied directly at the tumor site. One issue with regular photon radiation is that a large portion of the energy is expended when it hits the skin and other tissues prior to making contact with the tumor.
The issue with proton therapy, however, is that it isn’t often used for mesothelioma as many doctors simply prefer to use the more common photon radiation. Many hospitals also do not have the equipment to engage in proton therapy.
Internal Mesothelioma Radiation Therapy or Brachytherapy
Although internal mesothelioma radiation treatment (also referred to as brachytherapy) is rarely used, some doctors prefer it over external radiation.
With internal radiation therapy, small pods or seeds that are about the size of a grain of rice are placed on or near the tumor site. From there, they radiate energy similar to the type of energy that is beamed in externally. It can be applied during open surgery, but, in other cases, doctors will perform a minimally-invasive endoscopy to insert the irradiated seeds via a tube.
Internal radiation is particularly helpful for patients whose tumors are in hard to reach locations or are near vital organs. Brachytherapy also limits the damage done to healthy tissue as there is no beam coming from outside of the body.
There are three different types of methods doctors use for internal radiation and they include:
Involves the minimally-invasive implantation of seeds that emit a low dose of radiation for the period of as much as a week. The procedure itself is painless, but patients typically have to stay in the hospital without guests to avoid contaminating anyone else with their radioactivity.
Involves another minimally-invasive implantation of seeds that emit a higher dose of radiation over the course of a much shorter time (usually about 20 minutes). No hospital stay is required.
Involves the implantation of radioactive seeds during open surgery (such as an extrapleural pneumonectomy). The seeds actively provide radiation treatment to affected areas for about three months and will stay in the body permanently.
The side effects for all of these methods are limited because radiation is typically only emitted in about a 1 centimeter radius. As such, very little radiation makes its way to healthy organs or tissues.
Side Effects for Mesothelioma Radiation Treatment
There are a few side effects associated with radiation therapy. Most side effects are similar in nature to chemotherapy side effects because the issue involved is damage to healthy cells. With radiation therapy, however, the side effects are generally far less harsh because radiation is usually only applied to one location in the body (as opposed to systemically with chemotherapy).
The most common side effects associated with radiation therapy are:
- Skin issues – External beam radiation usually causes damage and irritation to the skin (dubbed “radiodermatitis”). Redness, rashes, and swelling are common. Peeling along with the darkening of skin can also occur.
- Fatigue – Damage to healthy cells will usually cause some form of tiredness in patients particularly as treatments progress. Major fatigue typically sets in within 2 to 4 hours after the procedure.
- Dry mouth and inflammation – Radiation therapy can often cause patients to experience dry mouth with occasional inflammation
Other symptoms are usually based on the type of mesothelioma. For instance, radiation therapy for pleural mesothelioma can temporarily make the symptoms of the disease worse.
- Difficulty breathing
- Chest pain
- Trouble with swallowing
For peritoneal mesothelioma, side effects are often related to abdominal or digestive issues. Nausea and vomiting are commonly seen whenever radiation therapy is applied to the abdominal area. If radiation therapy is applied at all to a patient with peritoneal mesothelioma, it will usually be to kill cancer cells at incision sites after surgery.
Side effects can also be amplified if other treatments are also being applied. For instance, a patient undergoing chemotherapy treatment may experience harsher symptoms related to radiation therapy because many of their healthy cells are already being damaged. The amount of radiation received on a regular basis and the overall health of the patient can also obviously affect the incidence of side effects.
For the most part, however, mesothelioma radiation therapy is a valuable treatment option for virtually all patients. When it is combined with other therapies like surgery and chemotherapy, it can improve survival rates drastically. Indeed, for many patients, radiation therapy can literally extend their lives.
As radiation therapy treatments are researched further, more progress will obviously be made in treating the disease and minimizing side effects. Radiation therapy will play a big role in ultimately finding a cure for mesothelioma down the road.
As for now, it offers a clinically proven way to reduce tumor sizes, decrease symptoms, and extend life spans.