Intensity-Modulated Radiation Therapy (IMRT) for Mesothelioma

What Is Intensity-Modulated Radiation Therapy?

IMRT is an advanced type of radiation therapy. Like many types of radiation therapy, it uses a linear accelerator, or linac machine, to aim high-energy X-rays at a tumor site inside a patient’s body.

The difference with IMRT is the linac machine is designed to move around the patient and hit the tumor site from multiple directions. A computer controls exactly how much energy the machine uses at each angle, based on imaging scans taken of the patient’s body.

In treatment for pleural mesothelioma, doses of radiation must be tailored to the exact size and shape of the tumor site. This is because pleural mesothelioma develops near the lungs and heart, which are very sensitive to radiation damage.

IMRT may be safer to use on pleural mesothelioma patients than older methods of radiation therapy. It is one of the most sophisticated forms of external beam radiation therapy.

How Is IMRT Used in Mesothelioma Treatment?

Doctors can use IMRT as a palliative treatment, intended to relieve a patient’s chest pain and improve quality of life. IMRT typically causes only mild side effects on its own, and it is safe to combine with chemotherapy or immunotherapy.

IMRT is also an important part of multimodal treatment to help patients live longer with pleural mesothelioma. In this approach, radiation therapy is usually the last step after surgery and chemotherapy.

Doctors use IMRT to try to kill any cancer cells left behind after surgery. A 2021 study published in The Lancet Oncology concluded extrapleural pneumonectomy after IMRT can be done with good early and long-term results, and other research supports its use in surgery patients who keep both lungs.

IMRT can treat primary mesothelioma tumors and metastases in other parts of the body, according to a 2021 study published in the Journal of Neurosurgery: Case Lessons. Mesothelioma radiation is commonly used to control painful tumors on the chest wall.

Types of Intensity-Modulated Radiation Therapy

One of the latest advances in external beam radiation is arc-based IMRT. It is designed to improve on the conventional technique known as “step and shoot” or “static fields.” Companies have developed different types of arc-based IMRT technology called helical tomotherapy and volumetric modulated arc therapy.

Arc-based IMRT delivers radiation continuously as the machine rotates in an arc around the patient. It controls its accuracy using a multileaf collimator, which has individual “leaves” that move in and out of the radiation’s path to make the beam the same shape as the tumor site.

Tamron Little

Verified Asbestos.com Survivor

Mesothelioma Survivor Thriving After IMRT

Tamron Little is a 17-year peritoneal mesothelioma survivor who credits early multimodal treatment for her long-term survival. Little underwent surgery, heated chemotherapy and IMRT. “The doctors thought the high-dose radiation had messed up my reproductive organs and I wouldn’t be able to have any more kids,” said Little. But she had 3 more children. “Every time I took another baby to see Dr. Levine, his eyes would just get wider and wider. He’d say, ‘So, this is yours, too? Tamron, you’re amazing. You’re a walking miracle.’”

Tamron Little

Verified Asbestos.com Survivor

Read Tamron’s Story

Helical Tomotherapy (HT)

In helical tomotherapy, the patient lies on a table that slides through a donut-shaped machine. The machine contains a linear accelerator that can revolve all the way around the patient.

A 2024 German study reported that IMRT is safe after surgery on patients with both lungs. In 2023, Turkish researchers reported a 2-year survival rate of 77.9% using surgery, chemotherapy and IMRT.

In 2021, a study in Translational Cancer Research reported that helical tomotherapy targeted tumors better than volumetric modulated arc therapy, but HT’s treatment delivery time was longer.

Volumetric Modulated Arc Therapy (VMAT)

VMAT also uses a linear accelerator that can rotate around a patient. It is much faster than other IMRT techniques, though, which reduces the risk of error because of the patient moving. A 2022 study published in Radiation Oncology reported that a machine-learning-based planning method optimized the delivery of radiation to tumors and reduced exposure to other organs.

Previous research has shown that patients could benefit from radiation therapy after having a lung removed. Recent studies support the idea that radiation therapy can also be tailored for patients who undergo lung-sparring surgery.

Because VMAT is a cutting-edge technology, though, not every hospital and cancer center is equipped to offer it.

Many people with mesothelioma travel to access top-notch treatment. Because it is rare, few oncologists know how to treat mesothelioma. Seeking a specialist helps people access the latest therapies.

Benefits and Risks of IMRT

IMRT treatment relies on careful planning and complex imaging techniques. With the right preparation, a computer can control exactly how much radiation each part of the patient’s body receives.

IMRT maximizes radiation exposure in the tumor site and minimizes exposure in healthy cells. This allows doctors to administer higher doses of radiation even when the tumor site is next to a sensitive organ such as a lung.

Of course, no treatment is 100% safe. Some patients do experience adverse reactions to IMRT. Radiation toxicity can lead to inflammation in lung tissue or pneumonitis. At its most extreme, it can cause irreversible damage by hardening the lung’s air sacs, which prevents them from inflating, making it impossible for the patient to breathe. Radiation can also damage the muscles in the heart.

Fortunately, improvements in IMRT techniques have reduced the risk of severe side effects, which has contributed to the rise of lung-sparring surgery in multimodal treatment. Radiation is not part of every mesothelioma patient’s treatment plan. Each patient must discuss with a mesothelioma specialist whether this treatment is appropriate for them.

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