Page 2 - Use of 5 ARI's in Clinical Practice: A Canadian Position

5ARIs in BPH treatment and
prostate cancer prevention
Why are 5ARIs used to prevent
prostate cancer?
5 ARIs inhibit the production of a hormone called
dihydrotestosterone (DHT) that stimulates prostate cells
to grow. It is therefore thought that these drugs might
also prevent the growth of prostate cancer. In two
clinical studies involving more than 20,000 men, men
who took a 5ARI (Proscar or Avodart ) were 25%
TM
TM
to 30% less likely to be diagnosed with a low-grade
prostate cancer than men who were not taking a
5ARI. In absolute terms, 18% of men taking a 5ARI were
diagnosed with low-grade prostate cancer compared
with 24% of men who were given a placebo or
“sugar pill”. Low-grade prostate cancer is the type
of cancer that is less aggressive and is sometimes
referred to as a “Gleason 6” prostate cancer. In the
same set of clinical studies, 1% of patients taking
Proscar or Avodart developed a more aggressive
TM
TM
or “high-grade” prostate cancer (Gleason 7 or higher)
compared with 0.5% of men who were taking a
placebo. Many experts believe that the explanation
for this slight increase in diagnoses of high-grade
prostate cancers is that these drugs shrink the normal
prostate cells and therefore reduce the amount of
PSA made by these cells. There is therefore a greater
chance that high-grade cancer, if present, will be
diagnosed. Other experts believe that a small ‘real’
increase in high-grade cancers cannot be excluded.
All agree that the risk, if real, is small.
How can 5ARIs be helpful to patients
who are on active surveillance for
their prostate cancer?
For men who have slow growing or very early prostate
cancers and/or may have other serious medical
conditions, active surveillance may be chosen as a
This publication is produced by
The information in the publication is not intended to convey medical advice or to substitute for direct consultation with a qualified medical
practitioner. The Canadian Urological Association disclaims all liability and legal responsibility howsoever caused, including negligence, for the
information contained in or referenced by this brochure.
© 2014. Canadian Urological Association. All rights reserved.
treatment option. Your urologist will discuss the pros
and cons of this with you. Active surveillance involves
close observation of patients who have decided not
to undergo immediate surgery or radiation therapy for
their prostate cancer. During active surveillance, the
cancer is carefully monitored for signs of progression.
This usually includes a PSA blood test and rectal
examination several times a year to evaluate for
changes. In clinical studies, 5ARIs have been shown to
prevent further rise of PSA levels in men on an active
surveillance program. This means that 5ARIs have a
potential to slow down the growth and progression of
prostate cancers.
Who can receive 5ARI therapy for
the prevention of prostate cancer?
Your urologist will discuss the pros and cons of the use
of a 5ARI for your case.
You may be a candidate to receive 5ARI therapy
for prostate cancer prevention if your PSA levels
are elevated and your prostate biopsy shows no
appearance of cancer. If you are at high risk of
developing prostate cancer, but you have not had
a prostate biopsy, you could also be considered to
receive a 5ARI to prevent prostate cancer. If you take
a 5ARI under these conditions, you will also need to
undergo a yearly PSA test.
For each of these possible uses, your doctor or
urologist will discuss the pros and cons. If you have
any questions concerning the 5ARI, speak with your
doctor.
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