Television viewers watching the "Dr. Oz Show" that aired on April 14, were faced with conflicting information regarding the use of thyroid shields during radiation-based procedures, such as mammograms, chest X-rays or dental X-rays.
According to the American College of Radiology (ACR), the TV talk show and a related e-mail that was circulated to thousands of American women incorrectly linked the radiation delivered during a mammography examination to an increased risk of developing thyroid cancer. As a result of the show and the e-mail, a number of women have been requesting that a thyroid shield be used during their mammography examinations.
"Some people have expressed a concern that the small amount of radiation received from a mammogram may increase their risk of developing thyroid cancer," explained Peter Apicella, M.D., Chief of Radiology at Salem Community Hospital. "However, this concern simply is not supported in scientific research.
"When a woman has a mammogram, the radiation dose to her thyroid is extremely low, because the thyroid is not directly exposed to the X-ray beam used to image her breast. Since the thyroid is not in the beam's direct path, it receives only a tiny amount of scattered X-rays, which is comparable to less than thirty minutes of natural radiation that we are all exposed to everyday, just living on the earth."
To give a better idea of the degree of thyroid cancer risk, a 40-year old woman, who receives a typical bilateral or 2-view mammogram once a year, has a lifetime risk of one in 158 million of the mammogram causing thyroid cancer. As a woman ages, her risk of thyroid cancer due to radiation exposure decreases even further, and the lifetime risk for a 70-year old woman receiving a typical, 2-view mammogram once a year drops to less than one in 740 billion.
Problems with the shield
Medical imaging professionals do not recommend the regular use of a thyroid shield during mammography exams, because it can blur important structures of the body and interfere with the positioning of the breast during the exam, along with affecting the interpretation of the results.
"The very slight risk of radiation exposure to the thyroid should be balanced against the fact that the use of the thyroid shield can interfere with the optimal positioning of the breast during the mammogram and the overall quality of the results of the exam," Dr. Apicella added.
"For example, use of the shield can result in artifacts, which are shadows that might appear on the mammogram and can distort the image. These factors may impact the accuracy of the mammogram and interfere with the diagnosis. In addition, use of the shield can result in the entire exam having to be repeated, which doubles the patient's radiation exposure."
Another concern is that some women may view this recent erroneous media report as a reason to put off or forego necessary breast imaging care.
"Mammography plays a critical part in diagnosing breast cancer," Dr. Apicella advised. "Mammograms can save lives by finding breast cancer as early as possible. For example, mammograms have been shown to lower the risk of dying from breast cancer by 35 percent in women over the age of 50."
Five important things to know about mammograms
1. They can save your life. Finding breast cancer early increases the chance of successful treatment as early as possible and reduces your risk of dying from the disease by 25-30 percent or more. Women should begin having mammograms yearly at age 40, or earlier if they're at a higher risk for breast cancer.
2. Don't be afraid. Mammography is a relatively fast procedure (about 15-20 minutes), and discomfort is minimal and tolerable for most women. The procedure is safe: there's only a very tiny amount of radiation exposure from a mammogram.
3. Get the best quality you can. If you have dense breasts or are under age 50, try to get a digital mammogram. A digital mammogram is recorded onto a computer so that radiologists can enlarge certain sections of the image and examine them more closely.
4. Mammography is our most powerful breast cancer detection tool. However, mammograms can still miss 20 percent of breast cancers that are simply not visible using this technique. Other important tools, such as breast self-exam or clinical breast examination, can be used as complementary tools, but they are no substitutes or replacements for a mammogram.
5. An unusual result requiring further testing does not always mean you have breast cancer. According to the American Cancer Society, about 10 percent of women (1 in 10) who have a mammogram will require more tests. Only 8-10 percent of these women will need a biopsy, and about 80 percent of these biopsies will turn out not to be cancer.
Peter Apicella, M.D., is a board certified radiologist and the Chief of Radiology at Salem Community Hospital. He is affiliated with Salem Radiologists, Inc., 2094 East State Street in Salem, 330-337-6140.