Radiation
Radiation therapy is an intense X-ray treatment to damage or kill cancer cells. Although not a cure for mesothelioma, radiation therapy nonetheless may be used at different stages of the disease to slow its growth. Radiation is often the main treatment for patients in weak health who are not candidates for surgery. When radiotherapy is used following surgical removal of the tumor, it is called adjuvant therapy. This type of therapy—surgery followed by radiation—has been demonstrated to reduce the local recurrence of the tumor and to improve the survival rate of patients with early-stage disease. Adjuvant therapy is also an essential part of the treatment of patients who undergo an extrapleural pneumonectomy.
Radiation therapy is important not just to control the growth of the tumor. Radiotherapy is also used to relieve the symptoms of mesothelioma by reducing pain, improving breathing, and easing the other physical problems caused by the cancer.
The kind of radiation treatment used for each patient will depend on several factors, including the size of the tumor and how close it is to vital organs, the stage of the disease, and whether other treatment options may also be used.
There are two primary types of radiation therapy used for mesothelioma patients: traditional external beam radiotherapy and brachytherapy. In addition, mesothelioma doctors are now employing a new form of radiotherapy, intensity-modulated radiation therapy (IMRT).
Adjuvant therapy
Adjuvant therapy is additional treatment to reduce the risk or cancer recurrence or increase the time before cancer recurs. Through the use of chemotherapy, radiation or other adjuvant therapies after a primary treatment like surgery, cancer specialists attempt to kill cancer cells that were left behind in the body but are too small to be seen. Adjuvant therapies, like all cancer treatments, also pose side effects that must be weighed in deciding whether to proceed with a possible treatment.
External Beam Radiation
External beam radiation therapy (EBRT) is routed to the site of the tumor with the use of linear accelerators. These machines generate high-energy external radiation beams that reach through the tissues into the areas where the tumor is found. To deliver the radiation precisely, doctors use computed tomography (CT) scans and PET scans to focus on the areas where the tumor is likely to reappear. Careful radiation planning allows the radiologist to direct a higher dose of radiation at the tumor tissue and to minimize the amount of normal tissue that will be exposed to this high dose of radiation.
Brachytherapy
Brachytherapy uses radioactive substances rather than radiation beams to deliver radiation treatments. The word “brachy” comes from the Greek, and means “short range.” This type of radiation therapy is different from external beam radiation, which is administered over a long range.
Because the radioactive substances used in brachytherapy will only work in the short range, they must be placed in or very near the target area of the body. This means that brachytherapy can be used for mesothelioma patients only by surgically implanting the radioactive substances. This therapy is generally performed during the same operation in which the tumor is removed, and is sometimes referred to as “Intraoperative Radiation Therapy” (IORT). For brachytherapy, the thoracic surgeon and radiation oncologist measure the areas of the chest cavity from which the mesothelioma and surrounding tissue cannot be fully removed. Then, a customized implant is created by weaving radioactive seeds into an absorbable mesh, known as a radioactive iodine seed implant. This flexible mesh is stitched into the body during surgery. The radiation from the implant is released over a three-month period, with a small amount of radioactivity still present for about a year. It is critical during this therapy not to increase a patient’s time in surgery too long, or complications may develop as a result of this delay. Doctors are still evaluating the overall benefits and risks of this procedure.
Intensity-modulated radiation therapy (IMRT)
Intensity-modulated radiation therapy (IMRT) is a new breakthrough in radiation oncology. The therapy allows for treatment of areas of the body that previously could not be treated with conventional radiation. IMRT for mesothelioma is delivered by a team of physicians, including a radiation oncologist, physicist and radiation therapist. The preliminary results for this new therapy suggest that the rate of local recurrence is significantly reduced for mesothelioma patients undergoing this treatment.
