PSA Q&A: The Prostate Cancer Screening Test
Based on the PSA
Test - Q&A
page of the National Cancer Institute
Edited (with Introduction) by Dr. Don Rose, Writer, Life Alert
What is the PSA test? Which men should get it done, and when? How often should seniors
take this test? Does
cover it? Why is the test performed? What are the downsides?
These and related issues are addressed in the article below. --Dr. Don Rose
PSA has two related meanings. Technically, it stands for Prostate-Specific Antigen,
yet the term is also used as shorthand for the prostate cancer screening test that
uses PSA. The goal of a PSA test is to look for warning signs that prostate cancer
may be more likely to occur. It does this by measuring the amount of PSA in the
Overview: Key Points
- Prostate-specific antigen (PSA) is a protein produced by the cells of the prostate
gland. The PSA test measures the level of PSA in the blood (see Question 1).
- The U.S. Food and Drug Administration (FDA) has approved the use of the PSA test
along with a digital rectal exam to help detect prostate cancer in men age 50 and
older. The FDA has also approved the PSA test to monitor patients with a history
of prostate cancer to see if the cancer has come back (recurred) (see Question 2).
- Doctors recommendations for screening vary (see Question 3).
- The higher a mans PSA level, the more likely it is that cancer is present, but there
are many other possible reasons for an elevated PSA level (see Questions 4 and 5).
The PSA screening test has limitations and is still controversial (see Questions
6 and 7).
1. What is the prostate-specific antigen (PSA) test?
Prostate-specific antigen (PSA) is a protein produced by the cells of the prostate
gland. The PSA test measures the level of PSA in the blood. The doctor takes a blood
sample, and the amount of PSA is measured in a laboratory. Because PSA is produced
by the body and can be used to detect disease, it is sometimes called a biological
marker or tumor marker.
It is normal for men to have low levels of PSA in their blood; however, prostate
cancer or benign (not cancerous) conditions can increase PSA levels. As men age,
both benign prostate conditions and prostate cancer become more frequent. The most
common benign prostate conditions are prostatitis (inflammation of the prostate)
and benign prostatic hyperplasia (BPH) (enlargement of the prostate). There is no
evidence that prostatitis or BPH cause cancer, but it is possible for a man to have
one or both of these conditions and to develop prostate cancer as well.
PSA levels alone do not give doctors enough information to distinguish between benign
prostate conditions and cancer. However, the doctor will take the result of the
PSA test into account when deciding whether to check further for signs of prostate
2. Why is the PSA test performed?
The U.S. Food and Drug Administration (FDA) has approved the PSA test along with
a digital rectal exam (DRE) to help detect prostate cancer in men age 50 and older.
During a DRE, a doctor inserts a gloved finger into the rectum and feels the prostate
gland through the rectal wall to check for bumps or abnormal areas. Doctors often
use the PSA test and DRE as prostate cancer screening tests; together, these tests
can help doctors detect prostate cancer in men who have no symptoms of the disease.
The FDA has also approved the PSA test to monitor patients with a history of prostate
cancer to see if the cancer has come back (recurred). An elevated PSA level in a
patient with a history of prostate cancer does not always mean the cancer has come
back. A man should discuss an elevated PSA level with his doctor. The doctor may
recommend repeating the PSA test or performing other tests to check for evidence
It is important to note that a man who is receiving hormone therapy for prostate
cancer may have a low PSA reading during, or immediately after, treatment. The low
level may not be a true measure of PSA activity in the mans body. Men receiving
hormone therapy should talk with their doctor, who may advise them to wait a few
months after hormone treatment before having a PSA test.
3. For whom might a PSA screening test be recommended?
Doctors recommendations for screening vary. Some encourage yearly screening for
men over age 50, and some advise men who are at a higher risk for prostate cancer
to begin screening at age 40 or 45. Others caution against routine screening, while
still others counsel men about the risks and benefits on an individual basis and
encourage men to make personal decisions about screening. Currently,
provides coverage for an annual PSA test for all men age 50 and
Several risk factors increase a mans chances of developing prostate cancer. These
factors may be taken into consideration when a doctor recommends screening. Age
is the most common risk factor, with nearly 70 percent of prostate cancer cases
occurring in men age 65
and older .
Other risk factors for prostate cancer include family history, race, and possibly
diet. Men who have a father or brother with prostate cancer have a greater chance
of developing prostate cancer. African American men have the highest rate of prostate
cancer, while Asian and Native American men have the lowest rates. In addition,
there is some evidence that a diet higher in fat, especially animal fat, may increase
the risk of prostate cancer.
4. How are PSA test results reported?
PSA test results report the level of PSA detected in the blood. The test results
are usually reported as nanograms of PSA per milliliter (ng/ml) of blood. In the
past, most doctors considered PSA values below 4.0 ng/ml as normal. However, recent
research found prostate cancer in men with PSA levels below 4.0 ng/ml . Many
doctors are now using the following ranges, with some variation:
- 0 to 2.5 ng/ml is low
- 2.6 to 10 ng/ml is slightly to moderately elevated
- 10 to 19.9 ng/ml is moderately elevated
- 20 ng/ml or more is significantly elevated
While there is no specific normal or abnormal PSA level, the higher a mans PSA level,
the more likely it is that cancer is present. However, because various factors can
cause PSA levels to fluctuate, one abnormal PSA test does not necessarily indicate
a need for other diagnostic tests. When PSA levels continue to rise over time, other
tests may be needed.
5. What if the test results show an elevated PSA level?
A man should discuss elevated PSA test results with his doctor. There are many possible
reasons for an elevated PSA level, including prostate cancer, benign prostate enlargement,
inflammation, infection, age, and race.
If no other symptoms suggest cancer, the doctor may recommend repeating DRE and
PSA tests regularly to watch for any changes. If a mans PSA levels have been increasing
or if a suspicious lump is detected during the DRE, the doctor may recommend other
tests to determine if there is cancer or another problem in the prostate. A urine
test may be used to detect a urinary tract infection or blood in the urine. The
doctor may recommend imaging tests, such as ultrasound (a test in which high-frequency
sound waves are used to obtain images of the kidneys and bladder), x-rays, or cystoscopy
(a procedure in which a doctor looks into the urethra and bladder through a thin,
lighted tube). Medicine or surgery may be recommended if the problem is BPH or an
If cancer is suspected, a biopsy is needed to determine if cancer is present in
the prostate. During a biopsy, samples of prostate tissue are removed, usually with
a needle, and viewed under a microscope. The doctor may use ultrasound to view the
prostate during the biopsy, but ultrasound cannot be used alone to tell if cancer
6. What are some of the limitations of the PSA test?
- Detection does not always mean saving lives: Even though the PSA test can detect
small tumors, finding a small tumor does not necessarily reduce a mans chance of
dying from prostate cancer. PSA testing may identify very slow-growing tumors that
are unlikely to threaten a mans life. Also, PSA testing may not help a man with
a fast-growing or aggressive cancer that has already spread to other parts of his
body before being detected.
- False positive tests: False positive test results (also called false positives)
occur when the PSA level is elevated but no cancer is actually present. False positives
may lead to additional medical procedures that have potential risks and significant
financial costs and can create anxiety for the patient and his family. Most men
with an elevated PSA test turn out not to have cancer; only 25 to 30 percent of
men who have a biopsy due to elevated PSA levels actually have prostate cancer .
- False negative tests: False negative test results (also called false negatives)
occur when the PSA level is in the normal range even though prostate cancer is actually
present. Most prostate cancers are slow-growing and may exist for decades before
they are large enough to cause symptoms. Subsequent PSA tests may indicate a problem
before the disease progresses significantly.
7. Why is the PSA test controversial?
Using the PSA test to screen men for prostate cancer is controversial because it
is not yet known if this test actually saves lives. Moreover, it is not clear if
the benefits of PSA screening outweigh the risks of follow-up diagnostic tests and
cancer treatments. For example, the PSA test may detect small cancers that would
never become life threatening. This situation, called overdiagnosis, puts men at
risk for complications from unnecessary treatment such as surgery or radiation.
The procedure used to diagnose prostate cancer (prostate biopsy) may cause side
effects, including bleeding and infection. Prostate cancer treatment may cause incontinence
(inability to control urine flow) and erectile dysfunction (erections inadequate
for intercourse). For these reasons, it is important that the benefits and risks
of diagnostic procedures and treatment be taken into account when considering whether
to undertake prostate cancer screening.
8. What research is being done to validate and improve the PSA test?
The benefits of screening for prostate cancer are still being studied. The National
Cancer Institute (NCI) is currently conducting the Prostate, Lung, Colorectal, and
Ovarian Cancer Screening Trial, or PLCO trial, to determine if certain screening
tests reduce the number of deaths from these cancers. The DRE and PSA are being
studied to determine whether yearly screening to detect prostate cancer will decrease
a mans chance of dying from prostate cancer.
Scientists also are researching ways to distinguish between cancerous and benign
conditions, and between slow-growing cancers and fast-growing, potentially lethal
cancers. Some of the methods being studied are:
- PSA velocity: PSA velocity is based on changes in PSA levels over time. A sharp
rise in the PSA level raises the suspicion of cancer.
- Age-adjusted PSA: Age is an important factor in increasing PSA levels. For this
reason, some doctors use age-adjusted PSA levels to determine when diagnostic tests
are needed. When age-adjusted PSA levels are used, a different PSA level is defined
as normal for each 10-year age group.
- PSA density: PSA density considers the relationship of the PSA level to the size
of the prostate. In other words, an elevated PSA might not arouse suspicion if a
man has a very enlarged prostate.
- Free versus attached PSA: PSA circulates in the blood in two forms: free or attached
to a protein molecule. With benign prostate conditions, there is more free PSA,
while cancer produces more of the attached form.
- Alteration of PSA cutoff level: Some researchers have suggested lowering the cutoff
levels that determine if a PSA measurement is normal or elevated. Researchers hope
that using these lower levels will increase the chance of detecting prostate cancer;
however, this may also increase false positive test results, leading to unnecessary
- Protein patterns: Scientists are also studying a test that
can rapidly analyze the patterns of various proteins in the blood. Researchers hope
that this technique can determine if a biopsy is necessary when a person has a slightly
elevated PSA level or an abnormal DRE.
For additional information about prostate cancer, contact the NCIs Cancer Information
Service (see below).
- Ries LAG, Eisner MP, Kosary CL, et al. (eds). SEER Cancer Statistics Review, 19752001,
National Cancer Institute. Bethesda, MD, 2004 (http://seer.cancer.gov/csr/1975_2001).
- Thompson IM, Pauler DK, Goodman PJ, et al. Prevalence of prostate cancer among men
with a prostate-specific antigen level 4.0 ng per milliliter. The New England Journal
of Medicine 2004; 350(22):22392246.
- Keetch DW, Catalona WJ, Smith DS. Serial prostatic biopsies in men with persistently
elevated serum prostate specific antigen values. The Journal of Urology 1994; 151(6):15711574.
National Cancer Institute (NCI) Resources
Cancer Information Service (toll-free):
Telephone: 18004CANCER (18004226237)
NCI's Web site: http://www.cancer.gov
LiveHelp, NCI's live online assistance:
This article is based on the
PSA Test - Q&A page
of the National Cancer Institute
website. The information provided here is, to the best of our knowledge, reliable
and accurate. However, while Life Alert always strives to provide true, precise
and consistent information, we cannot guarantee 100 percent accuracy. Readers are
encouraged to review the original article, and use any resource links provided to
gather more information before drawing conclusions and making decisions.
Dr. Don Rose writes books, papers and articles on computers, the Internet, AI, science
and technology, and issues related to seniors.
For more information about Life
and its many services and benefits for seniors available in New York
, California, Florida, and other
states nationwide -- please visit the following websites: