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Re: Low Dose Radiation More Effective at Killing Cancer Cells thanHigher Doses
I would be interested in seeing the dose rate as well.
--- "Stabin, Michael"
<michael.g.stabin@vanderbilt.edu> wrote:
>
>
http://interactive.snm.org/index.cfm?PageID=3115&EID=1191401
>
> Study Finds Low Dose Radiation More Effective at
> Killing Cancer Cells
> than Higher Doses
> Posted October 5, 2004
> Source: Johns Hopkins Medical Institutions
>
>
------------------------------------------------------------------------
> --------
>
> A new study shows that lower doses of radiation
> elude a damage detection
> "radar" in DNA and actually kill more cancer cells
> than high-dose
> radiation. With these findings, scientists believe
> they can design
> therapy to dismantle this "radar" sensor allowing
> more radiation to
> evade detection and destroy even greater numbers of
> cancer cells.
>
> Researchers at the Johns Hopkins Kimmel Cancer
> Center tested the
> low-dose radiation strategy on cultured prostate and
> colon cancer cell
> lines and found that it killed up to twice as many
> cells as high-dose
> radiation. The extra lethality of the low-dose
> regimen was found to
> result from suppression of a protein, called ATM
> (ataxia telangiectasia
> mutated) which works like a radar to detect DNA
> damage and begin repair.
>
>
> Theodore DeWeese, MD, who led the study, speculates
> that cells hit with
> small amounts of radiation fail to switch on the ATM
> radar, which
> prevents an error-prone repair process. DeWeese,
> chairman of the
> Department of Radiation Oncology and Molecular
> Radiation Sciences at
> Johns Hopkins, presented his evidence at the annual
> meeting of the
> American Society for Therapeutic Radiology and
> Oncology (ASTRO) on
> October 5 in Atlanta.
>
> "DNA repair is not foolproof-it can lead to mistakes
> or mutations that
> are passed down to other generations of cells,"
> DeWeese explained. "A
> dead cell is better than a mutant cell, so if the
> damage is mild, cells
> die instead of risking repair."
>
> Higher doses of radiation cause extreme DNA damage
> and widespread cell
> death, so the ATM damage sensor is activated to
> preserve as many cells
> as possible, protecting, ironically, the cancer
> cells targeted for
> destruction by the radiation.
>
> While the low-dose regimen works in cultured cells,
> it has not proved
> successful in humans. This has lead to effort by
> Hopkins scientists to
> study ways to use viruses that can deliver
> ATM-blocking drugs to the
> cells. Tests in animals are expected to begin soon.
>
> In the current study, colon and prostate cancer cell
> lines were treated
> with either high levels of radiation or small
> amounts spread over many
> days. Low-level radiation is defined as 10 times
> more stronger than
> normal background exposure, while high doses are
> 1,000 times stronger.
> Approximately 35 percent of colon cancer cells
> survived low-dose
> radiation as compared to 60 percent receiving
> high-dose. In prostate
> cancer cell lines, half of the cells survived
> low-dose radiation, while
> 65 percent survived higher doses.
>
> In the low-dose group, ATM activation was reduced by
> 40 to 50 percent.
> The researchers proved ATM inactivation was the
> culprit since low-dose
> irradiated cells fared better after ATM was
> reactivated with chloroqine,
> best known as a treatment for malaria.
>
> "Tricking cancer cells into ignoring the damage
> signals that appear on
> its radar could succeed in making radiation more
> effective in wiping out
> the disease," says DeWeese.
>
> This research was funded by the National Cancer
> Institute.
>
> Research participants from Johns Hopkins include
> Spencer Collis, Julie
> Schwaninger, Alfred Ntambi, Thomas Keller, Larry
> Dillehay, and William
> Nelson.
>
>
------------------------------------------------------------------------
> --------
>
>
> Michael G. Stabin, PhD, CHP
> Assistant Professor of Radiology and Radiological
> Sciences
> Department of Radiology and Radiological Sciences
> Vanderbilt University
> 1161 21st Avenue South
> Nashville, TN 37232-2675
> Phone (615) 343-0068
> Fax (615) 322-3764
> Pager (615) 835-5153
> e-mail michael.g.stabin@vanderbilt.edu
> internet www.doseinfo-radar.com
>
>
>
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=====
+++++++++++++++++++
"A devotee of Truth may not do anything in deference to convention. He must always hold himself open to correction, and whenever he discovers himself to be wrong he must confess it at all costs and atone for it."
Monhandas K. Gandhi, in "Autobiography"
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird@yahoo.com
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