July 10, 1998 Identifying men at risk for prostate cancer before
they develop the disease may soon become easier. Researchers have found
that a hormone called Insulin-like Growth Factor 1 (IGF-1) is linked to
a man's risk of prostate cancer.
for Prostate Cancer
IGF-1 keeps prostate cells alive and growing
regardless of whether the cells are normal or cancerous. The body gets rid
of damaged cells by means of a process called apoptosis, or programmed cell
death. IGF-1 interferes with this mechanism. Stimulating cell growth and
preventing cells from dying off, IGF-1 keeps damaged cells alive — which
increases the risk of cancer.
Led by Dr. June M. Chan of Harvard School of
Public Health in Boston, a research team tested blood from men enrolled
in the national Physicians' Health Study to see if those who developed
prostate cancer had, from the start, higher than normal levels of IGF-1.
Chan found this was the case.
The researchers compared blood samples
from 152 men diagnosed with prostate cancer during the study with 152
age-matched controls. They compared both IGF-1 and PSA (prostate specific
antigen, the marker currently used for early detection of prostate cancer).
The results showed an increased risk of prostate cancer in men with high
levels of IGF-1. Men with the highest levels had more than 4 times the
risk of prostate cancer than men with the lowest levels.
The researchers say that having a high IGF-1
level does not mean that a man will definitely develop prostate cancer.
A high IGF-1 level indicates that a man may be at greater risk for
prostate cancer, much the same as high cholesterol puts a man at increased
risk of heart disease.
Dr. Chan plans to do more research on 1GF-1
as a predictor of prostate cancer. Dr. Michael Pollak of McGill University
in Montreal, Quebec, Canada, a member of team, has already found links
between IGF-1 and risk of breast cancer. The researchers are now looking
at links with colon cancer.
If the new findings hold up, a blood test for
IGF-1 could identify men at risk of prostate cancer before anything shows
on a PSA test. It may also be possible to find ways of preventing prostate
cancer by reducing IGF-1 levels through diet or drugs
Chan and Pollack caution that men should not
yet seek testing to determine IGF-1 levels based on the results of this
preliminary study. But, if these findings are confirmed, men with high IGF-1
levels might be advised to undergo more frequent screening for prostate
This research was published in Science
(1998; 279:475, 563-566). A report is at ScienceNOW,
an online service available by subscription ($29.95 per year).
MJuly 10, 1998. Modified December 26, 1998
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