Mammography Screening and New Technologies

See BCA's Policy on Breast Cancer Screening and "Early Detection"

In order to make an informed decision about screening mammograms, women
must be given the following facts:

  1. Mammograms do not prevent breast cancer. They are a detection
device, not a prevention method.

  2. Mammography uses ionizing radiation, a known carcinogen that has
a cumulative effect on the body. The greater the radiation
exposure/dosage over a lifetime, the greater the risk of
radiation-induced cancer. This risk is highest in tissue in which cells
are rapidly changing, such as the growing breast tissue of adolescent
females.1 The Mammography Quality Standards Act (MQSA) regulations
specify that a single view dose shall not exceed 3.0 milligray (mGy) or
0.3 rad. The average dosage currently used for a single view mammogram
is 1.6 mGy (0.16 rads), a level that has dropped considerably from when
mammograms were first introduced.2

  3. The quality of mammography screening varies widely across the
country, depending on the age and maintenance of the equipment, the
skill of the technician who takes the x-rays, and the expertise of the
radiologist who interprets the films. It is important that the
mammography facility used be certified by the Food and Drug
Administration (FDA). Under the MQSA, all mammography facilities must
undergo an annual inspection and prominently display the certificate
issued by an FDA-accredited agency. To find out whether a mammography
center is currently certified, ask the center to show you their current
certification, or look for certified sites by zip code at
www.accessdata.fda.gov/
     scripts/cdrh/cfdocs/cfMQSA/search.cfm

  4. Mammograms do not always detect breast cancer-causing "false
negative" results. False negatives occur when a mammogram fails to
reveal a cancer that is present. In day-to-day practice, mammograms can
miss more than a quarter of all tumors.3

  5. Mammograms are not always accurate-causing "false positive"
results. False positives occur when a mammogram finds something in the
breast that, on biopsy, proves not to be cancer. As many as
three-fourths of all post-mammogram biopsy results turn out to be
benign lesions.4

  6. No studies have ever been conducted on the effectiveness of
mammography screening for women under 40 years of age. There is
therefore no evidence to support routine mammography screening of women
younger than 40.

  7. Mammography may not be effective in detecting breast cancer for
many women under the age of 50, or more accurately, women who are
pre-menopausal. Because the breast tissue of pre-menopausal women tends
to be denser than that of post-menopausal women, mammograms of younger
women may be more difficult to read.5 Therefore, in order to make
informed decisions regarding continuing mammography screening,
pre-menopausal women should be given information about the density of
their breasts and the effect of that density on the readability of
their mammograms. The risk of radiation exposure to pre-menopausal
women, combined with the high incidence of false negative readings for
mammograms of women in this group, means that routine mammography
screening of all women in this group may cause more harm than good.

  8. Women 40 years old or older who are pre-menopausal and who
consider themselves to be at high risk for breast cancer should consult
a breast cancer specialist for guidance on when to begin mammography
screening.

  9. There are conflicting studies examining the effectiveness of
screening mammograms for women between the ages of 50 and 65. Some of
these studies suggest that annual mammograms do not affect the breast
cancer mortality rate.6 Others suggest that the mortality rate could be
reduced for women in this group by as much as one third.7 Therefore, it
is unclear whether mammography screening is of benefit for women in
this age group.

 10. No studies have been done that look at the effectiveness of
mammography screening for women aged 65 or older.

There are a number of methods for detecting breast cancer that are not
in common use because they have not yet been shown to be more effective
than the current screening methods of mammography, breast self exam,
and clinical breast exam. Research is underway on the following
detection methods that may one day lead to a more reliable,
non-radiation based technology for detecting breast cancer.

   * Digital Mammography: already approved by the FDA, this technology
relies on x-rays of the breast, but digitizes the images, permitting
them to be transferred by computer. The FDA approved this technology
despite the lack of any evidence that digitizing mammography images
improved outcomes for women with breast cancer. Studies are currently
underway to evaluate whether digital mammograms are a more effective
technology than standard mammography. (See "Digital Imaging: A
Marketing Triumph," BCA Newsletter #62, November/December 2000)

   * Thermography (digital infrared imaging) uses sensors to measure
heat from the breast, based on the understanding that chemical and
blood level activity increase as cancer develops, and this activity
creates heat on the surface of the skin. The FDA has approved one
system of thermography, and trials are currently underway to evaluate
its effectiveness. Previous trials using older technology resulted in
inconsistent findings. One concern about thermography is that the
technology, while potentially very sensitive (it finds lots of breast
changes), is not very specific (we can't tell whether the thing it
finds is cancer or not). (See "Thermography: An Alternative to
Mammography?," BCA Newsletter #60, July/August 2000)

   * Ductal lavage uses a catheter inserted through the nipple of the
breast to remove fluid in the breast ducts. The fluid is then examined
under a microscope for evidence of cell changes that may indicate the
existence of cancer or precursors to cancer. Ductal lavage is not in
use for screening, though it is being used in some clinics in addition
to, rather than in replacment of, other screening methods such as
mammography. The invasive nature of the procedure may inhibit its
usefulness as a screening tool in the future. (See "For Whom the
Cells Toll," BCA Newsletter #65, May/June 2001)

   * MRI (Magnetic Resonance Imaging): this technology generates
images from signals sent out by nuclear particles in the magnetic field
to which the MRI machine exposes the breast. The technology is
extremely sensitive, creating challenges in developing uniform criteria
for evaluating the results. Until these challenges are resolved, it is
unlikely that this very expensive technology will be used for breast
cancer screening. Trials currently underway are evaluating MRI in
conjunction with mammography screening, not as a substitute.

   * Blood Test: Unlike the PSA test for prostate cancer, there is no
blood test used to screen for breast cancer, though there are blood
tests that can evaluate whether a woman carries a genetic mutation that
might increase her risk of developing breast cancer (See "Getting
into Our Genes," BCA Newsletter #67, September/October 2001), and
blood tests-like the AMAS test-that help monitor for the recurrence
of breast cancer (See "Blood Test May Help Detect and Monitor Breast
Cancer," BCA Newsletter #37, August/September 1996). Until research
resolves the dilemma posed by our inability to distinguish who will
benefit from or need breast cancer treatment from who won't, it is
ill-advised to advocate for a blood test for breast cancer, or for any
method of detecting breast cancer ?earlier.?

For more information on developing technologies for breast cancer
detection see: Institute of Medicine/National Resource Council,
Mammography and Beyond: Developing Technologies for the Early Detection
of Breast Cancer, National Academy Press: Washington DC, 2001.

1 Love, Susan, Dr. Susan Love's Breast Book, 3rd ed. , Perseus
Publishing: MA. 2000; p. 125.

2 Suleiman OH, "Mammography in the 1990s: The United States and
Canada," Radiology, 1999; 210, No. 2: 345-351e

3 24-27% cited in Yankaskas B et al., "Association of recall rates
with sensitivity and positive predictive values of screening
mammography," American Journal of Roentgen Ray Society, 2001 Sep;
177[3]:543-9.
28% cited in Poplack S et al., "Mammography in 53,803 Women from the
New Hampshire Mammography Network," Radiology, 2000 Dec; 217:832-840.

4 Institute of Medicine/National Resource Council, Mammography and
Beyond, National Academy Press: Washington DC. 2001; pg. 39.)

5 Love, Susan, Dr. Susan Love's Breast Book, 3rd ed. , Perseus
Publishing: MA. 2000; p. 125.

6 Olsen O and Gotzsche P, "Cochrane Review on Screening for Breast
Cancer with Mammography," The Lancet, 2001 Oct, 358:1340-1342; Miller
A, et al., "Canadian National Breast Screening Study-2: 13-Year
Results of a Randomized Trail in Women Aged 50-59 Years," Journal of
the National Cancer Institute, 2000 Sep, 92[18]: 1490-99

7 Nystrom L et al., "Breast cancer screening with mammography:
overview of Swedish randomised trials," Lancet, 1993 Apr
17;341[8851]:973-8

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