Popular Prostate Cancer Treatment May Encourage
Spread of the Disease
Androgen deprivation therapy (ADT) reduces male
hormones, called androgens, in the body.
Oct. 1, 2007 - A popular prostate cancer treatment
called androgen deprivation therapy may encourage prostate cancer cells
to produce a protein that makes them more likely to spread throughout
the body, a new study by Johns Hopkins researchers suggests.
Although the finding could eventually lead to
changes in this standard treatment for a sometimes deadly disease, the
Johns Hopkins researchers caution that their discovery is far too
preliminary for prostate cancer patients or physicians to stop using it.
The therapy is effective at slowing tumor growth, they emphasized.
David Berman, an assistant professor of pathology,
urology and oncology at The Johns Hopkins University School of Medicine,
and his colleagues identified the unsuspected potential problem with
treatments that suppress testosterone after discovering that the gene
that codes for the protein, called nestin, was active in lab-grown human
prostate cancer cells.
Curious about whether prostate cancer cells in
people also produce nestin, the researchers looked for it in cells taken
from men who had surgery to remove locally confined cancers of their
prostates and found none. But when they looked for nestin in prostate
cancer cells isolated from patients who had died of metastatic prostate
cancer - in which cancer cells spread out from the prostate tumor - they
found substantial evidence that the nestin gene was active.
What was different, Berman speculated, is that
androgen deprivation therapy, a treatment that reduces testosterone in
the body, is generally given only when prostate cancers become
aggressive and likely to metastasize.
| |
Hormone (Androgen Deprivation)
Therapy
American Cancer Society
Hormone therapy is also called androgen
deprivation therapy (ADT) or androgen suppression therapy. The
goal is to reduce levels of the male hormones, called androgens,
in the body.
The main androgens are testosterone and
dihydrotestosterone (DHT). Androgens, produced mainly in the
testicles, stimulate prostate cancer cells to grow. Lowering
androgen levels often makes prostate cancers shrink or grow more
slowly. However, hormone therapy does not cure prostate cancer.
Hormone therapy may be used in several
situations:
●
if you are not able to have surgery or radiation or can't
be cured by these treatments because the cancer has already
spread beyond the prostate gland
● if
your cancer remains or comes back after treatment with surgery
or radiation therapy
● as an
addition to radiation therapy as initial treatment if you are at
high risk for cancer recurrence
● before
surgery or radiation to try and shrink the cancer to make other
treatments more effective
There are several types of hormone therapy used
to treat prostate cancer.
Read more from American Cancer Society |
|
Because prostate cancer growth is typically
stimulated by testosterone, the treatment is thought to slow tumor
growth and weaken the disease. Patients who eventually die because their
disease metastasizes are almost certain to have received this type of
therapy, he says.
Speculating that depriving cells of androgens might
also, however, affect nestin expression, the researchers experimented on
a prostate cancer cell line that depends on androgens to grow. When they
removed androgens from the chemical mixture that the cells live in,
their production of nestin increased.
Aware that the nestin gene has long been suggested
to play some role in cell growth and development, Berman and his
colleagues used a bit of laboratory sabotage called RNA interference to
decrease the genetic expression of nestin and found that these cells
werent able to move around and through other cells nearly as well as
cells with normal nestin levels.
Prostate cancer cells with hampered nestin
expression were also less likely than normal prostate cancer cells to
migrate to other parts of the body when transplanted into mice. However,
while nestin expression seemed pivotal for metastasis in these
experiments, it didnt seem to make a difference in tumor growth.
What all this suggests is that nestin levels
increased when prostate cancer cells are deprived of androgens and may
encourage the cells to metastasize, says Berman.
Besides Berman, other Johns Hopkins researchers
involved in this study were Wolfram Kleeberger, M.D., G. Steven Bova,
M.D., Matthew E. Nielsen, M.D., Mehsati Herawi, M.D., Ph.D., Ai-Ying
Chuang, M.D., and Jonathan I. Epstein, M.D.
The research, published in the Oct. 1 issue of
Cancer Research, was funded by grants from the National Institutes of
Health, National Cancer Institute, Evensen Family Foundation, and German
Cancer Aid Foundation.
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Researchers Say They
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Octogenarians Not Too Old for Cancer Surgery, Say Mayo Clinic
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November 27, 2006
Prostate
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