When the PSA test was developed at Roswell Park Cancer Institute,
it was heralded as a major advance in the early detection of
prostate cancer, one of the most common cancers among men.
Advocates of the test say it has saved many men's lives.
But, increasingly, critics assail the test as unreliable,
useless, even a profit-driven public health disaster.
Those are tough words for T. Ming Chu.
Chu is the scientist whose research team in Buffalo in the 1970s
isolated the protein in the prostate that can indicate cancer and
developed the test to measure it. These days, he finds himself
having to defend his life's work.
"I would be the first person to say the PSA test is not perfect,"
he said during a recent interview at the cancer center. "But I
would also say that it is the best we currently have."
To Chu, the limitations of the PSA test have been known for many
years. He warned decades ago that the test was not a "magic
bullet."
PSA can't distinguish between aggressive cancers and slow-
growing tumors that won't ever pose a danger, leading to the
possibility that many healthy men will receive unnecessary
therapies that risk serious complications and drive up health
costs.
That possibility has become a disconcerting reality. A 2009 study
estimated that, since 1986, for every man helped by the PSA test,
about 20 men have been unnecessarily diagnosed with cancer and
treated.
To make matters more confusing for the estimated 192,000 men in
the United States diagnosed with prostate cancer annually, each
therapy has its proponents, and its pros and cons. But which
treatment is best remains unclear.
Until there is a better way of screening for prostate cancer, Chu
said that patients need to be educated about the implications of
PSA and doctors more careful about how they use the test.
The test, rather than prompting a rush to perform biopsies and to
treat, should initiate a conversation between doctor and patient
about the potential benefits and risks of surgery, radiation or
initially monitoring the disease to see if it progresses, he said.
The debate should not be about PSA, according to Chu, but about
the difficult decisions over what to do with the results.
"The PSA test needs to be done appropriately. It's not enough to
use it in a vacuum. You need to think," he said.
The PSA test received approval from the Food and Drug
Administration in 1986 as a way to monitor a prostate cancer
patient's response to treatment and to check for the recurrence of
disease. It was approved as a screening tool for the diagnosis of
cancer in 1994.
Since then, the test -- which measures the amount of prostate-
specific antigen in the blood -- has become a routine part of a
man's visit to the doctor, and millions of patients get tested
every year.
Advocates of the test note that, in the early 1980s, most men
learned they suffered from prostate cancer when it had metastasized
and was incurable. Only about 4 percent of men were diagnosed soon
enough to benefit from treatment.
Today, approximately 90 percent of all prostate cancers are
diagnosed at an early stage, when curative therapies can work, and
death rates from prostate cancer have significantly declined.
Years ago, Chu wrote that if just one life is saved by PSA, he
will consider the group effort in Buffalo to develop the test a
success.
"I feel even more intensely about this now," he said. "Over the
years, I've had friends and colleagues who told me how grateful
they are for the test."
Critics counter that other countries with relatively low use of
PSA screening also have experienced a decline in prostate cancer
death rates. They question whether what seems like longer survival
of screened patients is really just the result of earlier diagnosis
of many slow-growing cancers that will not pose harm in a man's
lifetime.
The potential complications of some therapies, including
incontinence and erectile dysfunction, can be serious. Moreover,
the cost of unneeded care runs into the billions of dollars.
Last year, two of the largest ongoing studies to date on the
value of PSA screening reported their results so far and failed to
resolve the controversy.
A team of U.S. researchers found no difference in the likelihood
of dying of prostate cancer between patients who received PSA tests
and those that didn't, although the study wasn't a true comparison
between screened and unscreened groups.
A European study determined that screening reduced the rate of
prostate-cancer-related deaths by 31 percent. But 1,410 men had to
be screened and 48 of them treated to prevent one death, prompting
questions over whether the benefit was worth the cost in medical
expenses and the risks to the men who received biopsies and
treatments they didn't need.
"If you think that 1,410 is too many people to screen, then what
is the right number?" asked Dr. James Mohler, a colleague of Chu's
who headed a panel that recently updated the prostate cancer
treatment guidelines of the National Comprehensive Center Network.
The not-for-profit alliance of cancer centers for the first time
urged doctors to consider active surveillance -- forgoing immediate
treatment and closely monitoring patients -- for individuals at low
risk of progressing to life-threatening prostate cancer.
He and Chu argue that the chance of overtreating prostate cancer
currently is no worse than mammography. They cite an international
review showing that for every 2,000 women screened regularly for 10
years, one will avoid dying from breast cancer. At the same time,
10 healthy women will be unnecessarily treated.
"Mass screening the population for prostate cancer is wrong,"
said Mohler, chairman of urology at Roswell Park. "But PSA is still
valuable. It's best used for early detection in younger men to
identify those at higher risk of dying from prostate cancer."
Organizations that develop medical care guidelines differ on
their advice.
The U.S. Preventive Services Task Force, which reviews scientific
evidence for tests and procedures, recommends against screening for
prostate cancer in men aged 75 years or older. It also concludes
that current evidence is insufficient to assess the balance of
benefits and harms of screening in men younger than 75.
The American Cancer Society does not recommend routine screening
for prostate cancer but doesn't rule it out either, recommending
that men make a decision after discussing the benefits and risks of
screening with their doctors.
The American Urological Association recommends screening and last
year dropped the age at which men should start to consider baseline
PSA testing to 40. The group calls for shared decision-making and
the use of patient decision aids to help men decide about
screening.
"Someone who wants a PSA test should get it, but doctors
shouldn't just be offering it to everyone as though they're
checking a box," said Richard M. Hoffman, a New Mexico internist
who conducted a national survey published last year on PSA doctor-
patient discussions.
The survey found that 30 percent of men received the blood work
for prostate cancer without their physician first discussing the
test with them.
That's not surprising, according to Hoffman, who said doctors
don't have the time.
Hoffman, who is affiliated with the not-for-profit Foundation for
Informed Medical Decision Making in Boston, Mass., said one
solution is greater adoption of written and audiovisual materials
to help patients understand the issues around testing.
Research shows the use of decision aids for prostate cancer and
other diseases can improve patients' knowledge, encourage
involvement in decision-making and reduce anxiety. But Hoffman said
the approach remains in its infancy.
e-mail: hdavis@buffnews.com
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Prostate cancer screening guidelines
Where to get information about prostate cancer screening
recommendations:
American Cancer Society
http://caonline.amcancersoc.org/cgi/content/full/caac.20066v1
U.S. Preventive Services Task Force
http://www.ahrq.gov/clinic/uspstf/uspsprca.htm American
Urological Association
http://www.auanet.org/content/guidelines-and-quality-care/
clinical-guidelines.cfm
National Comprehensive Cancer Network
http://www.nccn.com/prostate_cancer_overview.aspx
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