Drug shows promise in fight against prostate cancer
A re-evaluation of data from a significant prostate cancer study found that the
drug finasteride may help prevent prostate cancer.
In the study, the Prostate Cancer Prevention Trial (PCPT), 18,882 men were
given either finasteride or a placebo over a 7 year period. A comprehensive
re-evaluation of the study, published last month at Cancer Prevention Research
Online, shows that the men who took finasteride were 30 per cent less likely
to develop prostate cancer.
Initial study results, released in 2003, found that the men who took finasteride
were 25 per cent less likely to develop prostate cancer. However, an unsettling
finding was that the men who took finasteride seemed more likely to have high-grade
tumors, which tend to grow quickly. (Tumors considered high-grade were found
in 6.4 per cent of men who took finasteride, compared with 5.1 per cent of men
who took a placebo.)
The re-evaluation included careful examination of prostates removed from 500
study subjects who developed cancer. Researchers concluded that finasteride
did not encourage high-grade tumors and that it had only appeared so because
the drug shrinks the prostate and makes tumors easier to find.
“Finasteride actually shrank the prostate gland, so it appeared in initial
studies that more cancer was being found in biopsies of men who took the drug,”
said Mary Redman, PhD, a biostatistician at the Fred Hutchinson Cancer Research
Center in Seattle. (Source: American Association for Cancer Research website.)
“What that means is that the cancer took up more prostate tissue in men
who were treated, and that is why it was easier to find in biopsy. Cancer was
probably missed more often in biopsies of men on a placebo drug because the
prostate gland itself was larger.”
The dose of finasteride used in the study was 5 mg. Finasteride is approved
for treatment of enlargement of the prostate (BPH) in 5 mg doses and is also
approved as a hair loss treatment in 1 mg doses.
The PCPT studied men 55 and older and was done by the Southwest Oncology Group,
a cancer clinical trials cooperative with medical centers across the U.S.
“About 200, 000 men per year are detected with prostate cancer in the
United States,” said Ian Thompson, M.D., of the University of Texas Health
Sciences Center at San Antonio, who was lead author of the PCPT study and is
senior author of two studies re-analyzing the data. “And of those men,
in excess of 90 per cent are treated with radiation or surgery, which have some
side effects. About a third to a quarter of those men might never have been
diagnosed with prostate cancer had they been taking finasteride. That’s
a big deal.” (Source: Reuters UK)
The Prostate Cancer Research Foundation of Canada recommends that men past
40 have both a digital rectal exam (DRE) and a prostate-specific antigen (PSA)
FAST FACTS ABOUT PROSTATE CANCER
–An estimated 24,700 Canadian men will be newly diagnosed with prostate cancer
–An estimated 4,300 Canadian men will die from prostate cancer in 2008.
–A Canadian man has a 1 in 7 chance of being diagnosed with prostate cancer
in his lifetime, and a 1 in 27 chance of dying from it.
–A 70 year-old Canadian man has a 6 per cent chance of developing prostate
cancer by age 80.
(Statistics from the Canadian Cancer Society)
Age: Age is the most important risk factor for prostate cancer.
The risk for developing the disease starts rising significantly after age 50.
Race: Black men have an increased risk of getting prostate
Family History: Men who have relatives who have had prostate
cancer have a higher risk of getting the disease.
Diet: Men on high-fat diets may have a greater risk of getting
(*Source: Mayo Clinic)
ON THE WEB
more about the prostate cancer study.
Photo ©iStockphoto.com/Cliff Parnell