 |
jump to links
Falsely Negative Mammograms
Missed cancers are particularly common in pre-menopausal women
owing to the
dense and highly glandular structure of their breasts and increased
proliferation
late in their menstrual cycle (10, 11). Missed cancers are also
common in postmenopausal
women on estrogen replacement therapy, as about 20 percent develop
breast densities that make their mammograms as difficult to read
as those of
pre-menopausal women (12).
Interval Cancers
About one-third of all cancers— and more still of pre-menopausal
cancers, which
are aggressive, even to the extent of doubling in size in one month,
and more likely
to metastasize— are diagnosed in the interval between successive
annual mammograms
(2, 13). Pre-menopausal women, particularly, can thus be lulled
into a false
sense of security by a supposedly negative result on an annual
mammogram and
fail to seek medical advice.
Falsely Positive Mammograms
Mistakenly diagnosed cancers are particularly common in pre-menopausal
women,
and also in postmenopausal women on estrogen replacement therapy,
resulting in
needless anxiety, more mammograms, and unnecessary biopsies (14,
15). For
women with multiple high-risk factors, including a strong family
history, prolonged
use of the contraceptive pill, early menarche, and nulliparity— just
those
groups that are most strongly urged to have annual mammograms— the
cumulative
risk of false positives increases to "as high as 100 percent" over
a decade's
screening (16).
Overdiagnosis
Overdiagnosis and subsequent overtreatment are among the major
risks of mammography. The widespread and virtually unchallenged
acceptance of screening
has resulted in a dramatic increase in the diagnosis of ductal
carcinoma-in-situ
(DCIS), a pre-invasive cancer, with a current estimated incidence
of about 40,000
annually. DCIS is usually recognized as micro-calcifications and
generally treated
by lumpectomy plus radiation or even mastectomy and chemotherapy
(17).
However, some 80 percent of all DCIS never become invasive even
if left
untreated (18). Furthermore, the breast cancer mortality from DCIS
is the same—
about 1 percent— both for women diagnosed and treated early
and for those
diagnosed later following the development of invasive cancer (17).
That early
detection of DCIS does not reduce mortality is further confirmed
by the 13-year
follow-up results of the Canadian National Breast Cancer Screening
Study
(19). Nevertheless, as recently stressed, "the public is much
less informed about
overdiagnosis than false positive results. In a recent nationwide
survey of women,
99 percent of respondents were aware of the possibility of false
positive results
from mammography, but only 6 percent were aware of either DCIS
by name or
the fact that mammography could detect a form of 'cancer' that
often doesn't
progress" (20).
Quality Control
In 1992 Congress passed the National Mammography Standards Quality
Assurance
Act requiring the Food and Drug Administration (FDA) to ensure
that
screening centers review their results and performance: collect
data on biopsy
outcomes and match them with the original radiologist's interpretation
of the films
(21). However, the centers do not release these data because the
Act does not
require them to do so. It is essential that this information now
be made fully public
so that concerns about the reliability of mammography can be further
evaluated.
Activist breast cancer groups would most likely strongly support,
if not help to
initiate, such overdue action by the FDA.
More…
from the “Los Angeles Times”: Mammography Radiates
Doubt
European
Research Study confirms Mammography’s Ineffectiveness
REFERENCES
1. Gofman, J. W. Preventing Breast Cancer: The Story of a Major
Proven Preventable Cause of this Disease. Committee for Nuclear
Responsibility, San Francisco, 1995.
2. Epstein, S. S., Steinman, D., and LeVert,
S. The Breast Cancer Prevention Program,
Ed. 2. Macmillan, New York, 1998.
3. Bertell, R. Breast cancer and mammography. Mothering, Summer
1992, pp. 49– 52.
4. National Academy of Sciences– National
Research Council, Advisory Committee.
Biological Effects of Ionizing Radiation (BEIR). Washington, D.
C., 1972.
5. Swift, M. Ionizing radiation, breast cancer,
and ataxia-telangiectasia. J. Natl. Cancer
Inst. 86( 21): 1571– 1572, 1994.
6. Bridges, B. A., and Arlett, C. F. Risk
of breast cancer in ataxia-telangiectasia. N. Engl.
J. Med. 326( 20): 1357, 1992.
7. Quigley, D. T. Some neglected points in
the pathology of breast cancer, and treatment
of breast cancer. Radiology, May 1928, pp. 338– 346.
8. Watmough, D. J., and Quan, K. M. X-ray
mammography and breast compression.
Lancet 340: 122, 1992.
9. Martinez, B. Mammography centers shut down
as reimbursement feud rages on.
Wall Street Journal, October 30, 2000, p. A-1.
10. Vogel, V. G. Screening younger women at
risk for breast cancer. J. Natl. Cancer
Inst. Monogr. 16: 55– 60, 1994.
11. Baines, C. J., and Dayan, R. A tangled
web: Factors likely to affect the efficacy of
screening mammography. J. Natl. Cancer Inst. 91( 10): 833– 838,
1999.
12. Laya, M. B. Effect of estrogen replacement
therapy on the specificity and sensitivity
of screening mammography. J. Natl. Cancer Inst. 88( 10): 643– 649,
1996.
13. Spratt, J. S., and Spratt, S. W. Legal
perspectives on mammography and self-referral.
Cancer 69( 2): 599– 600, 1992.
14. Skrabanek, P. Shadows over screening mammography.
Clin. Radiol. 40: 4– 5, 1989.
15. Davis, D. L., and Love, S. J. Mammography
screening. JAMA 271( 2): 152– 153, 1994.
16. Christiansen, C. L., et al. Predicting
the cumulative risk of false-positive mammograms. J. Natl.
Cancer Inst. 92( 20): 1657– 1666, 2000.
17. Napoli, M. Overdiagnosis and overtreatment:
The hidden pitfalls of cancer screening.
Am. J. Nurs., 2001, in press.
18. Baum, M. Epidemiology versus scaremongering:
The case for humane interpretation
of statistics and breast cancer. Breast J. 6( 5): 331– 334,
2000.
19. Miller, A. B., et al. Canadian National
Breast Screening Study-2: 13-year results of a
randomized trial in women aged 50– 59 years. J. Natl.
Cancer Inst. 92( 18): 1490– 1499,
2000.
20. Black, W. C. Overdiagnosis: An under-recognized
cause of confusion and harm in
cancer screening. J. Natl. Cancer Inst. 92( 16): 1280– 1282,
2000.
21. Napoli, M. What do women want to know.
J. Natl. Cancer Inst. Monogr. 22: 11– 13,
1997.
Excerpted
from “Dangers and Unreliability
of Mammography: Breast Examination is a Safe, Effective and
Practical Alternative”,
by Samuel S. Epstein, Rosalie Bertell, and Barbara Seaman, International
Journal of Health Services, Volume
31, Number 3, 2001
CONTACT:
Samuel S. Epstein, M.D.
Chairman, Cancer Prevention Coalition
c/o University of Illinois at Chicago
School of Public Health, M/C 922
2121 W. Taylor Street
Chicago, IL 60612
epstein@uic.edu
|
