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From http://www.preventcancer.com/patients/mammography/ijhs_mammography.htm :
DANGERS OF SCREENING MAMMOGRAPHY
Mammography poses a wide
range of risks of which women worldwide still remain uninformed.
Radiation Risks
Radiation from routine mammography poses significant cumulative risks of
initiating and promoting breast cancer. Contrary to conventional assurances
that radiation exposure from mammography is trivial- and similar to that
from a chest X-ray or spending one week in Denver, about 1/ 1,000 of a
rad (radiation-absorbed dose)- the routine practice of taking four films
for each breast results in some 1,000-fold greater exposure, 1 rad, focused
on each breast rather than the entire chest. Thus, premenopausal women
undergoing annual screening over a ten-year period are exposed to a total
of about 10 rads for each breast. As emphasized some three decades ago,
the premenopausal breast is highly sensitive to radiation, each rad of
exposure increasing breast cancer risk by 1 percent, resulting in a cumulative
10 percent increased risk over ten years of premenopausal screening, usually
from ages 40 to 50; risks are even greater for "baseline" screening
at younger ages, for which there is no evidence of any future relevance.
Furthermore, breast cancer risks from mammography are up to fourfold higher
for the 1 to 2 percent of women who are silent carriers of the A-T (ataxia-telangiectasia)
gene and thus highly sensitive to the carcinogenic effects of radiation;
by some estimates this accounts for up to 20 percent of all breast cancers
annually in the United States.
Cancer
Risks from Breast Compression
As early as 1928, physicians were warned to handle "cancerous breasts
with care- for fear of accidentally disseminating cells" and spreading
cancer. Nevertheless, mammography entails tight and often painful compression
of the breast, particularly in premenopausal women. This may lead to distant
and lethal spread of malignant cells by rupturing small blood vessels in
or around small, as yet undetected breast cancers.
Delays in Diagnostic Mammography
As increasing numbers of premenopausal women are responding to the ACS's
aggressively promoted screening, imaging centers are becoming flooded and
overwhelmed. Resultingly, patients referred for diagnostic mammography
are now experiencing potentially dangerous delays, up to several months,
before they can be examined.
UNRELIABILITY OF MAMMOGRAPHY
Falsely Negative
Mammograms
Missed cancers are particularly common in premenopausal women owing to
the dense and highly glandular structure of their breasts and increased
proliferation late in their menstrual cycle. Missed cancers are also common
in post-menopausal women on estrogen replacement therapy, as about 20 percent
develop breast densities that make their mammograms as difficult to read
as those of premenopausal women.
Interval Cancers
About one-third of all cancers- and more still of premenopausal 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. Premenopausal 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
Mammogram
Mistakenly diagnosed cancers are particularly common in premenopausal women,
and also in postmenopausal women on estrogen replacement therapy, resulting
in needless anxiety, more mammograms, and unnecessary biopsies. 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.
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.
However, some 80 percent of all DCIS never become invasive even if left
untreated. 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. 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. Nevertheless, as recently stressed, "the public is much less
informed about over-diagnosis 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".
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.
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.
FAILURE TO REDUCE BREAST CANCER MORTALITY
Despite the long-standing claims, the evidence that routine mammography
screening allows early detection and treatment of breast cancer, thereby
reducing mortality, is at best highly questionable. In fact, "the
overwhelming majority of breast cancers are unaffected by early detection,
either because they are aggressive or slow growing". There is supportive
evidence that the major variable predicting survival is "biological
determinism- a combination of the virulence of the individual tumor plus
the host's immune response," rather than just early detection.
Claims for the benefit of screening mammography in reducing breast cancer
mortality are based on eight international controlled trials involving
about 500,000 women. However, recent meta-analysis of these trials revealed
that only two, based on 66,000 postmenopausal women, were adequately randomized
to allow statistically valid conclusions. Based on these two trials, the
authors concluded that "there is no reliable evidence that screening
decreases breast cancer mortality- not even a tendency towards an effect."
Accordingly, the authors concluded that there is no longer any justification
for screening mammography; further evidence for this conclusion will be
detailed at the May 6, 2001, annual meeting of the National Breast Cancer
Coalition in Washington, D. C., and published in the July report of the
Nordic Cochrane Centre.
Even assuming that high quality screening of a population of women between
the ages of 50 and 69 would reduce breast cancer mortality by up to 25
percent, yielding a reduced relative risk of 0.75, the chances of any individual
woman benefiting are remote. For women in this age group, about 4 percent
are likely to develop breast cancer annually, about one in four of whom,
or 1 percent overall, will die from this disease. Thus, the 0.75 relative
risk applies to this 1 percent, so 99.75 percent of the women screened
are unlikely to benefit.
THE UNITED STATES VERSUS OTHER
NATIONS
No nation other than the United States routinely screens premenopausal
women by mammography. In this context, it may be noted that the January
1997 National Institutes of Health Consensus Conference recommended against
premenopausal screening, a decision that the NCI, but not the ACS, accepted.
However, under pressure from Congress and the ACS, the NCI reversed its
decision some three months later in favor of premenopausal screening.
The U. S. overkill extends to the standard practice of taking two or more
mammograms per breast annually in postmenopausal women. This contrasts
with the more restrained European practice of a single view every two to
three years.
More information at
http://chetday.com/mammogram.html
http://www.awakenedwoman.com/breast_cancer.htm
The misuse of mammography in the management of breast cancer PubMed abstract
Long-term effects of false-positive mammograms PubMed abstract
Breast cancer: Are mammograms unsafe?
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