WASHINGTONDespite some promising new technologies,
traditional x-ray film mammography remains the gold standard in screening for
breast cancer, a committee of the Institute of Medicine (IOM) has concluded.
The committee’s review included several breast imaging tools
already approved for breast cancer detection by the Food and Drug
Administration (FDA) and others, such as optical imaging, still in development.
"Several show promise as adjuncts to mammography, but to
date, none have been proved to be superior to conventional mammography for
routine screening," said committee chair Joyce C. Lashof, MD, professor
emerita of the University of California, Berkeley, School of Public Health.
Dr. Lashof said that ultrasound and magnetic resonance imaging
(MRI) can aid in diagnosis and may be of value in screening selected groups of
women. Digital mammography offers technical advantages, she said, but has not
yet been shown to be more accurate than film mammography. "Many other new
technologies are at a relative early stage of development, and thus more
research is needed to adequately assess their accuracy and effectiveness,"
The IOM, part of the National Academy of Sciences, established
its study committee in 1999 to look closely at the current state-of-the-art of
early breast cancer detection. Funding for the effort came from seven
independent foundations and individuals.
The committee expressed concerned that new imaging technologies
approved by the FDA for diagnostic purposes were also being used for screening
without adequate proof of efficacy.
Both she and Janet K. Baum, MD, noted that only one large trial
has compared the breast cancer screening powers of film and digital
mammography. Among about 7,000 women, the study found no statistical difference
in detection rates, said Dr. Baum, associate professor of radiology, Harvard
Medical School, and director of breast imaging, Beth Israel Deaconess Medical
Dr. Baum added, however, that digital mammography has technical
advantages over film mammography, including easier image retrieval, storage,
and transmission, and easier use with computerized detection systems.
She noted that one hope for digital mammography is that it will
improve detection rates in women with denser breasts. A multicenter study to
assess that potential, with a planned enrollment of 50,000, will start this
summer. The protocol calls for each woman to receive a screening with both film
and digital mammography, be rescreened 1 year later, and be followed for a
total of 3 years.
Panel vice chair I. Craig Henderson, MD, adjunct professor of
medicine, University of California, San Francisco, added that all breast
cancers are not the same; to avoid overdiagnosis, it is crucial that
researchers learn how to distinguish more virulent from less dangerous tumors.
The committee made several recommendations:
Government support for development of new breast cancer
detection technologies should continue to emphasize research on the basic
biology and etiology of breast cancer and on the creation of classification
schemes for breast cancer lesions based on molecular biology.
Breast cancer specimen banks should be expanded, and
researchers’ access to patient samples should be enhanced.
The FDA should develop and apply consistent criteria for
approval of screening and diagnostic devices and tests.
For new screening technologies, FDA approval and coverage
decisions by the Health Care Financing Administration (HCFA) and private
insurers should depend on evidence of improved clinical outcome.
The National Cancer Institute (NCI) should create a
permanent infrastructure for testing the efficacy and clinical effectiveness of
new detection technologies as they emerge.
HCFA should analyze current Medicare and Medicaid
reimbursement rates for mammography screening, including a comparison with
other radiologic techniques, to determine whether they adequately cover the
total costs of providing the procedure.
The Health Resources and Services Administration should
undertake or fund a study to analyze trends in specialty training for breast
cancer screening among radiologists and radiologic technologists, and examine
factors affecting the decision of practitioners to enter or remain in the
Until health insurance becomes more universally available,
Congress should expand the Centers for Disease Control and Prevention screening
program to reach a higher fraction of eligible women, and state legislatures
should participate in the federal Breast and Cervical Treatment Act by
providing funds for cancer treatment of eligible women.
The NCI should sponsor large randomized trials every 10 to
15 years to reassess the effect of accepted screening modalities on clinical
The NCI, in conjunction with the American College of
Radiology Imaging Network or the Breast Cancer Surveillance Consortium, should
sponsor further studies to define more accurately the benefits and risks of
screening mammography in women over age 70.