PSA
Results Vary From One Test To The Next
Study Author Recommends
Two Tests Before Prostate Biopsy
A new study shows
 that
results from a common blood test used to look for a protein
called prostate-specific antigen (PSA) can vary widely from
test to test. Men with an abnormally high PSA value on
one day may have a normal result on a later retest, authors
of the new report say in the Journal of the American
Medical Association (JAMA).
A PSA test is used
to help detect prostate cancer. PSA is a protein in blood that increases
in men with prostate cancer, as well as those with other, benign
prostate conditions.
Since PSA levels in
blood may vary from day to day, "it's probably prudent to recheck
a level" at least six weeks after an earlier test before advising
a patient to have a biopsy, says study author Dr. James Eastham,
a surgeon at Memorial Sloan-Kettering Cancer Center in New York
City.
PSA
Testing Value Still Being Debated
Although PSA testing
is often encouraged for men over 50, its value as an early-detection
tool is not certain, say some experts, and evidence is mixed
about whether the exam can prevent deaths from prostate cancer.
"Even with flaws,
it is a very useful tool," says Dr. Eastham. "You just have
to use it in an appropriate way."
More than 220,000
American men will be diagnosed with prostate cancer this year,
and nearly 29,000 will die of the disease, according to the
American Cancer Society (ACS). One man in six
will be diagnosed with prostate cancer during his lifetime,
but only 1 man in 32 will die of this disease.
In addition to an
annual physical exam that includes blood, urine, and possibly
other lab tests, the ACS suggests consulting
your physician about the evaluation of the prostate gland. Tests
usually include a digital rectal exam (DRE) and the PSA test.
A DRE and a PSA test
are usually conducted annually for men over the age of
50. Men in high-risk groups, such as African-Americans, or those
with a strong family history of prostate cancer, may be advised
by their physicians to be tested at a younger age.
In the latest research, Dr. Eastham's group followed 972 men
enrolled in a seven-year prostate cancer prevention study.
The participants, whose average age was 62, had five separate
PSA tests drawn over a four-year period.
About one in five
men had a PSA level considered high - over 4 nanograms per milliliter
of blood - on at least one reading. Yet on a subsequent test,
roughly half of these men had fallen back into the normal range
for the protein, suggesting the spike was not a signal of prostate
cancer.
Second
PSA Test Recommended
The ACS
says experts at many major scientific and medical organizations,
such as the US Preventive Services Task Force,
the National Cancer Institute (NCI), and Centers
for Disease Control and Prevention (CDC), are discussing
PSA testing and its value.
The NCI
states that "not all screening tests are helpful, and most have
risks such as bleeding or infection due to a biopsy of the prostate
for an abnormal PSA blood test. For this reason, scientists
at the National Cancer Institute are studying many screening
tests to find out how useful they are, and to determine the
relative benefits and harms."
"A single abnormal
PSA level should be viewed with caution," the researchers write
in JAMA. Physicians should confirm the reading
"before expensive or invasive tests, such as a prostate biopsy,
are recommended," the authors said.
Always consult your
physician for more information.
What Are the Symptoms
of Prostate Cancer?
There are usually
no specific signs or symptoms of early prostate cancer.
The following are
the most common symptoms of prostate cancer. However, each individual
may experience symptoms differently.
Symptoms may include:
-
weak or interrupted flow of urine
-
urinating often (especially at night)
-
difficulty urinating or holding back
urine
-
inability to urinate
-
pain or burning when urinating
-
blood in the urine or semen
-
nagging pain in the back, hips, or
pelvis
-
difficulty having an erection
The symptoms of prostate
cancer may resemble other conditions or medical problems.
Always consult your
physician for a diagnosis.
Online
Resources
(Our Organization
is not responsible for the content of Internet sites.)
Centers
for Disease Control and Prevention (CDC)
Men's
Health Network
National
Cancer Institute (NCI) Prostate Cancer: Screening and Testing
National
Institutes of Health (NIH)
US
Preventive Services Task Force
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July 2003
PSA
Results Vary From One Test To The Next
PSA
Testing Value Still Being Debated
Second
PSA Test Recommended
What
Are the Symptoms of Prostate Cancer?
What
Are Risk Factors for Prostate Cancer?
Online
Resources
What
Are Risk Factors for Prostate Cancer?
In general, all men
are at risk for prostate cancer. However, there are specific
risk factors that increase the likelihood that certain men will
develop the disease, including the following:
age
Age is a risk factor for prostate cancer, especially men age
50 and older. More than 80 percent of all prostate cancers are
diagnosed in men over the age of 65.
race
Prostate cancer is nearly twice as common among African-American
men than it is among Caucasian-American men. Japanese and Chinese
men native to their country have the lowest rates of prostate
cancer. When Chinese and Japanese men immigrate to the US, they
have an increased risk and mortality rate from prostate cancer,
when compared to their native populations.
diet
Studies suggest that the diet consumed in Western industrialized countries
may be one of the most important contributory factors for developing
prostate cancer. Consider the following information regarding diet and
its effect on the risk for prostate cancer:
-
fat
Studies suggest that men who eat a high-fat diet may have a greater
chance of developing prostate cancer.
-
fiber
Dietary fiber intake may influence circulating levels of testosterone
and estradiol, which, in turn, may decrease the progression of
prostate cancer.
-
soy protein
Besides lower fat intake, another major difference between Asian
and American diets is the consumption of soy, averaging 35 g/day
per capita. Soy contains isoflavone which, in some studies, have
been found to inhibit the growth of prostate cancer.
-
vitamin E and selenium
Vitamin E, an antioxidant, combined with selenium, has been shown
to inhibit tumor growth in lab animals.
-
carotenoids
Carotenoids containing lycopenes have been shown to inhibit the
growth of human prostate cancer cells in tissue cultures (cells
grown in the laboratory). The primary source of lycopenes is processed
tomatoes in tomato juice and tomato paste.
-
herbal preparations
Combination herbal preparations should be used with caution
as reported side effects have included venous thrombosis,
breast tenderness, and loss of libido. Many herbal preparations
have not been studied in men with prostate cancer.
obesity
Obesity has also been associated with some common cancers,
including hormone-dependent tumors such as prostate, breast,
and ovarian cancer.
having a vasectomy,
BPH (benign prostatic hyperplasia), or STD (sexually transmitted
disease)
Researchers have looked at whether men who have had
a vasectomy, BPH, or those who have been exposed to a sexually
transmitted disease are at increased risk for prostate cancer.
Some studies suggest a link, while others do not support these
claims.
family history
of prostate cancer
Having a father or brother with prostate cancer doubles a man's
risk of developing this disease. The risk is even higher for
men with several affected relatives, particularly if the relatives
were young at the time of diagnosis.
genetic factors
Some genes, when altered or mutated, give a higher
risk for uncontrolled cell growth, which, in turn, can lead
to tumor development. These genes have various names, but overall
are referred to as "cancer susceptibility genes."
About 9 percent of
all prostate cancers and 45 percent of cases in men younger
than age 55 can be attributed to a cancer susceptibility gene
that is inherited as a dominant trait (from parent to child).
Always consult your
physician for more information.
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