(30-06-10) Study shows how radiation causes breast cancer

by S. L. Baker, features writer


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 cancer
Common 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...

Source: NaturalNews

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In evidenza

"L'informazione presente nel sito serve a migliorare, e non a sostituire, il rapporto medico-paziente."

Per coloro che hanno problemi di salute si consiglia di consultare sempre il proprio medico curante.