Originally published June 9 2010
Study shows how radiation causes breast cancer
by S. L. Baker, features writer
(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 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...
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