JHMI Office of Communications and Public Affairs

September 19, 2000
MEDIA CONTACT: Marjorie Centofanti
PHONE: (410) 955-8725
E-MAIL: mcentofanti@jhmi.edu

Annual PSA Tests For Men May Not Be Best, Says Joint Study

"...strong evidence indeed that what we're doing now is probably not the
best way"


The standard, widely-used approach to screen men for prostate cancer --
annual PSA tests after age 50 --  may be less efficient and cost-effective
than one that tests men earlier and less frequently, according to a study
in today's Journal of the American Medical Association.

The study used a computer model to simulate the outcomes of prostate cancer
detection under a variety of scenarios.  Researchers varied the age at
which men would first start regular PSA testing, varied the interval
between tests and varied the PSA cutoff level urologists use for
recommending a biopsy.

The favored scenario showed that screening men twice before they're 50 --
once at age 40 and again at age 45 -- and then following that with
every-other-year screening, beginning at age 50, "would substantially
reduce the cost we spend on prostate screening. It would also prevent more
deaths from prostate cancer, compared with existing screening practices,"
says Hopkins urologist H. Ballentine Carter, M.D., a member of the research
team.

Compared with the standard way of screening, he says, "the model showed
you'd do 3,000 fewer PSA tests and 200 fewer biopsies for every 1,000 men
screened over a lifetime."

"What we've found doesn't mean the world should change screening practices
tomorrow.  It is, after all, a computer simulation," Carter adds. "But
because this simulation is trustworthy, it's very strong evidence indeed
that what we're doing now is probably not the best way."

Researchers from Johns Hopkins, Merck Research labs and the University of
North Carolina collaborated on the study.

Under current guidelines for prostate cancer screening, men get an annual
PSA (prostate specific antigen) test after age 50, with a follow-up biopsy
if the PSA level is higher than 4 nanograms per milliliter of blood.
"There's no science to show that you should start at age 50 and test
annually," says Carter. "That strategy was adopted because it seemed
reasonable, especially in light of women getting an annual mammogram for
breast cancer.  But," he adds, "prostate cancer tends to grow and progress
more slowly than breast cancer, so yearly screening is probably not necessary."
"In fact," Carter adds, "no good clinical research exists to confirm that
PSA screening in general reduces deaths from prostate cancer.  Such very
expensive randomized studies, where large numbers of patients are followed,
are now under way in Europe and the United States.  But our study assumes
PSA screening is useful and goes on to focus on the best way to do it."

The model simulated a population of 1 million men, followed, beginning at
age 40, for 40 years.

Under the "ground rules" the researchers used as a basis for their model --
real data on the way prostate cancer progresses over the years, on results
of treatment, on who gets the disease, on what PSA tests and biopsies can
show -- the researchers first produced a basic model of the natural history
of unchecked prostate cancer. "That's what you'd get with no screening,"
says Carter.

Then they modeled different PSA screening strategies.  The researchers
compared each strategy, with outcomes translated into the number of deaths
it would prevent and into the number of PSA tests and biopsies that
strategy required.

The researchers began their work because one of Carter's earlier studies
showed younger men tend to have a higher cure rate from prostate cancer,
probably because their tumors are smaller and more confined.  "Screening
earlier and detecting the disease at a younger age may decrease the number
of deaths from prostate cancer in this country," says Carter.

"We can't translate this yet into universal guidelines.  The purpose of
this study now is to raise awareness.  What needs to take place are
confirmatory studies with real patients.  But based on this study, some
physicians and their patients may choose to begin PSA testing before age 50."
The research was funded by grants from the National Cancer Institute.

Other researchers were Kevin S. Ross, now a medical student at Hopkins and
formerly with the University of North Carolina, Chapel Hill; Harry A.
Guess, with the University of North Carolina and the Merck Research labs in
Blue Bell, Pa.; and Jay Pearson, Ph.D., with Hopkins and Merck.

Related Web sites:
For more information on prostate research at Hopkins:
http://prostate.urol.jhu.edu/
For information on PSA testing and prostate cancer:
http://www.cancer.org/m2m/m2mpsa.html or
http://www.afud.org/conditions/psaduring.html

                                                                  

 

TC-KA3ES