Drug May Help Prevent Prostate Cancer
New Guidelines for Healthy Men to Talk to Their Doctors About Taking Proscar
Feb. 24, 2009 -- Millions of healthy men may benefit from talking to their
doctors about taking the drug Proscar to prevent prostate cancer, according to
new guidelines from the American Society of Clinical Oncology and the American
The recommendation is based on evidence gathered from 15 clinical trials,
including the large Prostate Cancer Prevention Trial (PCPT) of over 18,000 men
aged 55 and older. In that study, men who took a Proscar pill daily for one to
seven years were about 25% less likely to develop prostate cancer than men who
took a placebo.
Proscar is a type of drug known as a 5-alpha reductase inhibitor (5-ARI).
These drugs lower the level of the hormone dihydrotestosterone, which can
contribute to the growth of prostate cancer. Currently, 5-ARIs are used to
treat certain noncancerous conditions, including male-pattern baldness and
benign prostatic hyperplasia.
Another 5-ARI, called Avodart, is also being tested as a prostate cancer
preventive. While the guidelines call for discussing the whole class of drugs
with your doctor, only Proscar has been proven to reduce cancer risk to date,
notes says Barnett S. Kramer, MD, MPH, associate director for disease
prevention at the National Institutes of Health and co-chair of the guidelines
Prostate cancer is the second most common cause of cancer death among men.
The American Cancer Society estimates that 186,320 American men were diagnosed
with the disease last year.
The key recommendations in the guideline include:
- Men with a prostate-specific antigen (PSA) level of 3.0 or below who are
screened regularly, or who plan to get yearly PSA tests and who show no
symptoms, are encouraged to talk with their doctor about the risks and benefits
of taking a 5-ARI to further prevent their likelihood of getting prostate
- Men who are already taking a 5-ARI for other conditions should talk to
their doctor about continuing to use the drug for the prevention of prostate
"Since age is the key risk factor for prostate cancer, I'd suggest that
all men aged 55 and older talk to their doctor about the risks and
benefits," Kramer says.
The discussion is likely to be complicated. Among the factors to
- When the findings from PCPT first came out, use of Proscar appeared to be
associated with an increased risk of developing high-grade tumors, which are
more likely to spread. A more thorough look at all the evidence now suggests
"that the increase in high-grade cancers among men on Proscar was most
likely an artifact," Kramer tells WebMD. Still, uncertainty exists.
- The therapy could prove costly and it is unclear whether insurance
companies will pay. According to Kramer, "you would have to treat 71
healthy men for about seven years to prevent one case of prostate
- Prostate cancers are so slow-growing that many cancers prevented by the use
of 5-ARIs may never cause harm in the first place.
- It is still not known whether taking a 5-ARI will reduce the risk of dying
from prostate cancer or extend life expectancy.
- There are possible, though typically reversible, side effects associated
with the use of 5-ARIs. They include an increased risk of erectile dysfunction
and a decrease in libido and ejaculation volume.
- The use of 5-ARIs carries certain benefits, chiefly a decreased risk of
lower urinary tract symptoms such as having trouble urinating.