Study shows how radiation causes breast cancer
Jun 14, 2010
(NaturalNews) It's well-established that exposure to ionizing radiation
can trigger mutations and other genetic damage and cause normal cells
to become malignant. So it seems amazing how mainstream medicine
frequently dismisses the idea that medical imaging tests from
mammograms to CT scans could play much of a role in causing breast
cancer. Take this example from the web site for Cornell University's
Program on Breast Cancer and Environmental Risk Factors:
In
answer to the question "Is ionizing radiation a cause of breast
cancer?", the Cornell experts say "Yes" and note ".. female breast
tissue is highly susceptible to radiation effects." But then they
pooh-pooh the possible hazard from mammography x-rays saying the risk
…"should not be a factor in individual decisions to undergo this
procedure. The same is true for most diagnostic x-ray procedures."
If
that's not confusing enough, they turn around and state: "Nonetheless,
unnecessary radiation exposures should be avoided and continued
vigilance is required to ensure that the benefits associated with
specific procedures outweigh the future risks."
Why radiation causes breast cancerCommon sense suggests there is plenty
of reason to be worried about radiation causing breast cancer. And now
there's a new reason to be concerned. Researchers at the U.S.
Department of Energy's Lawrence Berkeley National Laboratory (Berkeley
Lab) have discovered that radiation exposure can alter cells'
microenvironment (the environment surrounding cells). And that greatly
raises the odds future cells will become cancerous.
The reason
is that signals from a cell's microenvironment, altered by radiation
exposure, can cause a cell's phenotype (made up of all its biochemical
and physical characteristics) to change by regulating or de-regulating
the way a cell uses its genes. The result can be a cell that not only
becomes pre-cancerous but that passes this pre-malignant condition on
to future cells.
"Our work shows that radiation can change
the microenvironment of breast cells, and this in turn can allow the
growth of abnormal cells with a long-lived phenotype that have a much
greater potential to be cancerous," Paul Yaswen, a cell
biologist and breast cancer research specialist with Berkeley Lab's
Life Sciences Division, said in a statement to the press.
"Many
in the cancer research community, especially radiobiologists, have been
slow to acknowledge and incorporate in their work the idea that cells
in human tissues are not independent entities, but are highly
communicative with each other and with their microenvironment," he added.
For
their study, Yaswen and his research teams used human mammary
epithelial cells (HMECs), the cells that line breast ducts, where most
breast cancers start. When placed in a culture dish, the vast majority
of HMECs display a phenotype that allows them to divide between five
and 20 times until they become what is known as senescent, or unable to
divide. However, there are also some variants of these cells which have
a phenotype that allows them to continue dividing for many weeks in
culture. Known as a vHMEC phenotype, this type of breast cell arises
spontaneously and is more susceptible to malignancy because it lacks a
tumor-suppressing protein dubbed p16.
To find out what radiation
exposure does to the cellular environment and how it could impact the
future of cell behavior, the Berkeley Lab scientists grew sets of HMECs
from normal breast tissue in culture dishes for about a week. Then they
zapped each set with a single treatment of a low-to-moderate dose of
radiation and compared the irradiated cells to sets of breast cells
that had not been irradiated.
The results, just published in the on-line journal Breast Cancer Research,
showed that four to six weeks after the radiation exposure, the normal
breast cancer cells had stopped dividing far earlier than they would
have normally -- and this premature cell senescence had accelerated the
outgrowth of vHMECS.
"However, by getting normal cells to
prematurely age and stop dividing, the radiation exposure created space
for epigenetically altered cells that would otherwise have been filled
by normal cells. In other words, the radiation promoted the growth of
pre-cancerous cells by making the environment that surrounded the cells
more hospitable to their continued growth," Yaswen explained in the
press statement.
The researchers pointed out that the levels of
radiation used in their experiments were not as much as a woman would
be exposed to during a single routine mammogram but were comparable to
those a woman could receive during a CT scans or radiotherapy "and
could represent sources of concern."
Of course, women are
often pushed to get annual mammograms, raising their overall radiation
exposure through the years. And, as NaturalNews has reported, previous
research has already provided compelling evidence linking mammography
to breast cancer.
For example, a report published in the Journal of the American Medical Association's Archives of Internal Medicine
found that the start of screening mammography programs throughout
Europe has been associated with increased incidence of breast cancer (http://www.naturalnews.com/024901.html). And a Johns Hopkins study published in the Journal of the National Cancer Institute concluded radiation exposure from mammograms could trigger malignancies in women at risk for genetic breast cancer (http://www.naturalnews.com/025560_c...).
For more information:
http://www.ncbi.nlm.nih.gov/pubmed/...
http://envirocancer.cornell.edu/fac...
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