"A single breast-specific gamma imaging (BSGI) or positron emission mammography (PEM) examination carries a lifetime risk of inducing fatal cancer greater than or comparable to a lifetime of annual screening mammography starting at age 40," said the study's author, R. Edward Hendrick, Ph.D., clinical professor of radiology at the University of Colorado-Denver, School of Medicine in Aurora, Co.
The risks and benefits of screening mammography are under constant scrutiny. Meanwhile, newer breast imaging technologies, such as BSGI and PEM have been approved by the U.S. Food and Drug Administration (FDA) and introduced into clinical practice. Preliminary studies have shown both to be promising at detecting cancer; however, both involve the injection of radioactive material into the patient.
BSGI uses a high-resolution gamma camera that allows for imaging with mild compression of the breast along with an injection of a nuclear radiotracer, which is absorbed at a higher rate by cancerous cells. In PEM, radioactive material is injected into the body to measure metabolic activity and determine the presence of disease. Other technologies, not yet approved by the FDA, include dedicated breast CT and digital breast tomosynthesis.
Dr. Hendrick reviewed recent studies on radiation doses from radiologic procedures and organ doses from nuclear medicine procedures, along with Biologic Effects of Ionizing Radiation (BEIR) VII age-dependent risk data, to estimate the lifetime risk of radiation-induced cancer incidence and death from breast imaging exams using ionizing radiation.
Two-view digital mammography and screen-film mammography were found to have an average lifetime risk of fatal breast cancer of 1.3 and 1.7 cases, respectively, per 100,000 women aged 40 years at exposure and less than one case per one million women aged 80 years at exposure. Annual screening mammography (digital or screen-film) performed in women from age 40 to age 80 is associated with a lifetime risk of fatal breast cancer of 20 to 25 cases in 100,000.
"Two-thirds of mammography units in the U.S. are now digital, which, on average, exposes the patient to an even lower radiation dose than screen-film," Dr. Hendrick said. "Manufacturers and breast centers continue to take steps to lower radiation doses on digital mammography systems without negatively affecting image quality."
Dedicated breast CT and digital tomosynthesis were both found to have an average lifetime risk of fatal breast cancer of 1.3 to 2.6 cases, respectively, per 100,000 women 40 years of age at exposure.
A single BSGI exam was estimated to involve a lifetime risk of fatal cancer 20 to 30 times that of digital mammography in women aged 40 years, while the lifetime risk of a single PEM was 23 times greater than that of digital mammography. In addition, while mammography only slightly increases a woman's risk for breast cancer, BSGI and PEM may increase the risk of cancers in other organs as well, including the intestines, kidneys, bladder, gallbladder, uterus, ovaries and colon.
People are exposed to radiation from natural sources all the time. The average person in the U.S. receives an effective dose of about 3 millisieverts (mSv) per year from naturally occurring radioactive materials and cosmic radiation from outer space. The average effective dose from two-view screen-film (0.56 mSv) or digital mammography (0.44 mSv) is equivalent to approximately two months of natural background radiation, while the effective doses from BSGI (6.2 mSv) and PEM (9.4 mSv) exams equal approximately two to three years of natural background radiation exposure.
Currently, no one is advocating using PEM or BSGI as a screening method to replace mammography. These exams are typically performed on women with suspicious breast lesions and in women with dense breasts who are difficult to examine with other techniques. Despite the increased radiation dose, these exams have shown promise in detecting cancer accurately and may have a good risk-benefit ratio for some specific indications.
"The primary tool for breast cancer screening is still mammography, which has a very low radiation dose and a very low lifetime risk of cancer induction," Dr. Hendrick said. "The risk of missing a breast cancer because mammography is not done far outweighs the tiny risk of mammography causing a breast cancer."
He added that the subset of women under 40 who are known to be at higher risk of breast cancer should consider being screened with breast ultrasound or breast MRI, both of which deliver no ionizing radiation and have sensitivities to breast cancer that are unaffected by higher breast density.
"Radiation Doses and Cancer Risks from Breast Imaging Studies." Disclosures: Dr. Hendrick is a consultant to GE Healthcare regarding digital breast tomosynthesis and a member of the medical advisory boards of Koning (dedicated breast CT) and Bracco (MR contrast agents). No support from any industry source was provided for this study, and the study results have not been shared with or in any way influenced by commercial entities.
Radiology is edited by Herbert Y. Kressel, M.D., Harvard Medical School, Boston, Mass., and owned and published by the Radiological Society of North America, Inc. (http://radiology.rsna.org/)
RSNA is an association of more than 44,000 radiologists, radiation oncologists, medical physicists and related scientists committed to excellence in patient care through education and research. The Society is based in Oak Brook, Ill. (RSNA.org)
For patient-friendly information on breast imaging, visit RadiologyInfo.org.
Linda Brooks | EurekAlert!
Can radar replace stethoscopes?
14.08.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
Novel PET imaging method could track and guide therapy for type 1 diabetes
03.08.2018 | Society of Nuclear Medicine and Molecular Imaging
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.
Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
14.08.2018 | Information Technology
14.08.2018 | Life Sciences
14.08.2018 | Life Sciences