Prostate Cancer Prevention
Introduction |
The Prostate Cancer Prevention Trial |
Why should finasteride prevent prostate cancer development? |
Where can you find more information?
Introduction
The major increase in the number of cases of prostate cancer identified
in recent years has led
researchers to consider the possibility of
preventing prostate cancer development in selected
individuals at
highest risk of this disease. The availability of new pharmaceuticals
with relatively
minor side effects has also helped allow researchers to
carry out careful investigation of this
possibility.
The Prostate Cancer Prevention Trial
The Prostate Cancer Prevention Trial (PCPT) was organized by the National Cancer Institute in 1993
as the first
ever large-scale trial for the prevention of prostate cancer in the USA.
It is designed to test
whether a pharmaceutical known as finasteride or
Proscar (made by Merck & Co.) will prevent men from developing prostate cancer.
This trial will involve 18,000 men who are at least 55 years old. The minimum age limit of 55 was
chosen because older men are much more likely to develop prostate cancer than young men.
According to the National Cancer Institute, of every 100 cases of prostate cancer discovered, 98 are in
men over 55 years of age.
The 18,000 men who take part in this trial will be divided into two
groups at random. Half the men
(about 9,000) will be asked to take one
finasteride tablet per day for 7 years. The other 9,000 men
will be
asked to take a placebo tablet every day for 7 years. A placebo is an
inactive tablet that looks
exactly like the active tablet in the trial
(in this case finasteride). However, none of the men in the
trial, or
their doctors, will know whether an individual patient is taking
finasteride or the placebo.
This system is known as "double blinding"
and means that there is the highest possible chance that the
results of
the trial will not be affected by the individual knowledge of trial
participants or their
personal physicians. At various times, the two
groups of men will be compared to see if there is any
difference
between the rates of prostate cancer development in the two groups.
We had previously reported information suggesting that this trial is not enrolling patients as
fast as was hoped, and also that patients were dropping out of the trial at an
unexpectedly high rate. We are delighted to report that this is
not the case. Accrual and randomization of patients to this trial
are in fact above the requirements originally projected, and
drop-out rates are within the expected limits. Additional information is
available in a Letter to the Editor
from Phyllis Goodman, the lead statistician working on this trial.
Why should finasteride prevent prostate cancer development?
There is no absolute proof that finasteride can prevent the development of prostate cancer -- even in
laboratory animals.
However, the way in which finasteride works -- also called its mechanism
of
action -- means that it has certain effects which could lower the
risk of men developing clinically
evident prostate cancer within a
specific time period. For example, finasteride can reduce the level of
a hormone known as dihydrotestosterone or DHT in the prostate, and we
know that DHT is important
in the development and growth of prostate
cancer.
The really important reason why finasteride is the first
pharmaceutical ever to be tested in a large
clinical trial for
prevention of prostate cancer is that it appears to have an
exceptionally low level of
side effects. According to most
authorities, even those side effects that have been documented are
comparatively mild. In this trial, an active pharmaceutical is being
given to men who are perfectly
healthy. This means that the
pharmaceutical (finasteride) must be as safe as possible, so that the
risks
associated with taking the pharmaceutical for seven years are
very little more than the risks associated
with taking the inactive
placebo.
Where can you find more information?
There is a considerable amount of information available about the Prostate Cancer
Prevention Trial. In the first place, many physicians across the
country are actively involved in helping to enroll patients into this
trial. If you think that you might like to participate in this trial,
the first step would be to ask
your personal physician if he or she can
give you further information.
Additional information is also
available at the following on-line sites:
Questions and Answers About the Prostate Cancer Prevention Trial
Prostate Cancer Prevention Trial Will Recruit 18,000 Men
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