Here's more hormone news:
By Stephen Hart
ABCNEWS.com
Jan. 21 -Researchers may have
discovered a marker that flags
prostate cancer in much the same
way high cholesterol warns of heart
disease.
It's an ordinary hormone called IGF-1
-for insulin-like growth factor-and if early
research holds up in further testing, it could
give doctors a new way to determine how
early to treat men with prostate cancer.
Around 200,000 men are diagnosed with
prostate cancer every year in the United
States, and about 40,000 die from it. Even
before symptoms occur, a blood test called
prostate-specific antigen, or PSA, can
indicate the presence of cancer, which is
often successfully treated with surgery and
radiation.
But some men suffer side effects from the
treatments, including bowel and bladder
irritation and urinary incontinence. And
nearly everyone treated for prostate cancer
suffers sexual dysfunction, at least during the
year following treatment. Measuring both
PSA and IGF-1 could allow physicians to
delay treatment for some patients whose
cancer was found very early, and to warn
cancer-free men who run a high risk of
prostate cancer in the future.
Supplementing PSA Test
After comparing blood specimens from 152
men with prostate cancer to samples from
152 healthy men, cancer researcher Michael
Pollak of the McGill University in Toronto
and Harvard University epidemiologist June
M. Chan, concluded that IGF-1 may be an
accurate marker for prostate cancer.
"The strength of the association between
IGF-1 and prostate cancer is in the same
ballpark as the association between
cholesterol and heart disease," says Pollak.
All of the men whose blood was analyzed
were participants in the Physician's Health
Study, a research effort in which the health
and lifestyle habits of thousands of men were
tracked over time. Working with blood
samples taken in 1982, at the beginning of
the larger study, Pollak and Chan divided the
men into four groups, from those with the
lowest levels of IGF-1 to the highest. They
also tested the blood samples for PSA
levels.
They found that men who had normal
PSA tests but were in the highest IGF-1
group were nearly five times as likely to have
developed prostate cancer as men with the
lowest levels of IGF-1.
Furthermore, men with positive PSA tests
but low IGF-1 were only four times as likely
as men with normal PSA levels to have been
diagnosed with prostate cancer during the
study period. But men who had positive
PSA tests and were in the highest IGF-1
group stood nearly 18 times the chance of
getting prostate cancer.
Treatment Controversy
Eventually, most experts agree, nearly all
men who have positive PSA tests will get
prostate cancer. IGF-1, on the other hand,
measures the relative risk of getting cancer in
the future.
Not all prostate cancers act alike, Pollak
explains, and "there has been this
controversy about whether everybody with
early prostate cancer needs to have surgery
or radiation. IGF-1 may turn out to be an
important tool in helping decide who needs
surgery, who needs radiation and who could
be safely just watched."
"I don't think it's something that would be
put into practice any time in the near future,"
cautions Chan. "Our results are pretty early
findings, but they did suggest that you could
enhance diagnosis using a standard PSA and
a test for IGF-1 levels."
Both researchers hope their study will
spawn more investigation into use of IGF-1
levels to detect prostate cancer early. If
larger studies bolster their results, a blood
test for IGF-1 could become a routine part
of every middle-aged man's yearly checkup. |
