By the mid-twentieth century, ionizing radiation was seen as useful in the treatment of a wide variety of malignant and benign medical conditions. However, it became apparent that radiation therapy also could have significant side effects.  We now know that ionizing radiation may cure many cancers, but it also has the potential to cause a cancer to develop ten to twenty years later.  Most patients have a less than 1% chance of developing a cancer in the future by receiving a course of radiation treatment.  There are a few people who have genetic conditions that put them at higher risk of develop cancers if treated with ionizing radiation.  

     Such considerations now cause the use of ionizing radiation for benign diseases to be more restricted than in the past. There must be a balance of risk and benefit. Debate continues over the list of benign disorders that may be treated with ionizing radiation, but many radiation oncologists would consider treatment for keloids, desmoid tumors, heterotopic bone formation prophylaxis, arteriovenous malformations in the brain, and coronary artery restenosis.

    In-depth Information

    Keloids

     Keloids represent an exuberant overgrowth of fibrous tissue, often in the form of an overgrown scar following some sort of trauma.  They sometimes grow to form an appreciable mass, but they are not cancerous.  Patients seek treatment for these lesions because they are disfiguring or uncomfortable.  Surgical excision alone usually leads to re-growth of the keloid; however, a very effective treatment is to remove the keloids surgically and then start a short course of radiation within 24 hours. Radiation can be tried alone but is less successful.  Steroid injections are sometimes tried as an alternative approach for keloids.

    Desmoids

     Desmoids are masses of connective tissue that may occur at various sites, but they can cause particular problems in the abdomen where there is the potential to compress a loop of intestine or a ureter. As with keloids, one useful approach is to combine surgery with irradiation. If surgery seems inadvisable, radiation treatment alone can be considered, often with satisfactory response. 

    Heterotopic Bone Formation

     Heterotopic bone formation refers to the growth of abnormal bone, often interfering with the motion of a joint.  The most frequent problem is seen after a hip fracture:  formation of abnormal bone in the area of the hip decreases mobility at the joint and interferes with the ability to walk.  It is often necessary to operate to remove the abnormal bone. A single large fraction of radiation will then suffice to prevent further formation of abnormal bone. The temporomandibular joint of the jaw is another site that may require treatment which may consist of a series of smaller radiation fractions rather than one larger one.

    Arteriovenous Malformations in the Brain

     Arteriovenous malformations (AVMs) are small clusters of blood vessels in which the high-pressure arterial system is more closely connected to the low-pressure venous system and lacks the usual ntervening capillary bed.  These abnormalities are particularly threatening when they are present in the brain, as they could be the precursor site to a stroke.  A particularly effective method to deal with these lesions is stereotactic  radiosurgery, a specialized technique that is available at Emory University.  In stereotactic radiosurgery, a single large radiation fraction is delivered to a very small area in the brain by the use of CT scan planning, rigid immobilization of the patient's head, and a rotational technique so that the entrance of the beam through normal tissues is distributed over a wide area, converging at the point to be treated.  The great majority of AVMs so treated will regress gradually over months to one or two years.

    Restenosis of Coronary Arteries

     Coronary artery disease leading to heart attacks remains a major lethal disease process in the United States. In coronary artery disease, the build-up of plaque material on the inside wall of the coronary arteries gradually narrows the lumen, which is the open passageway through which blood flows. Eventually, the plaque material or a small blood clot closes the lumen completely, preventing a coronary artery from carrying blood supply to the heart muscle itself.  That deprives the heart muscle of needed oxygen and nutrients, and the resultant crisis in heart muscle function represents a heart attack.  The narrowing of the artery lumen is referred to as stenosis.  

     One response to this problem was the bypass graft—patching in a piece of vein or artery to bypass the narrowed or obstructed part of the coronary artery.  An alternative approach utilized in recent years is known as angioplasty. In this procedure a thin tube known as a catheter is passed through a blood vessel to the area of obstruction and a balloon at the end of the catheter is then inflated, crushing the plaque and opening the narrowed lumen. A problem with angioplasty has been that in about 30% of cases, some of the cells in the wall of the coronary artery will proliferate and narrow or close the lumen of the artery once more.  Recently, ionizing radiation has been used to eliminate the unwanted proliferating cell population in the wall of the artery.  

    Research & Clinical Trials

     Emory University has been in the forefront of this effort to prevent coronary artery restenosis, developing a device that will permit a short path-length radioactive material (beta emitter) to be inserted temporarily in the lumen of the diseased part of a coronary artery following angioplasty.  The department participates in national clinical trials evaluating the benefit of adding radiation at the time of angioplasty.  Click here to learn more about our clinical trials center.

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