What is PSA? Do I need a PSA Test?

The PSA test is just one of a number of tests for early detection of prostate cancer. If you want to jump to diagnosis of prostate cancer, go to Earlier Detection: Finding Prostate Cancer.

The PSA test is a simple blood test to measure how much PSA (prostate specific antigen) a man has in his bloodstream at a given time. The PSA test is the most effective test currently available for the early detection of prostate cancer.

Since the PSA test came into use in the United States, the death rate for prostate cancer has fallen by one third. In 2005, a Harvard study found that men who have a yearly PSA test are nearly three times less likely to die from prostate cancer than those who don't have annual screenings.

University of Pittsburgh Cancer Institute says PSA testing and digital rectal examination (DRE) "are crucial in detecting prostate cancer in its early stages, when it usually produces no physical symptoms."

PSA testing is also used to monitor the progress of prostate cancer which has already been diagnosed.

On this page:

Related sections: Detection >> Staging >> Biopsy >> Decisions

Prostate specific antigen (PSA)

PSA starts out in the fluid that carries sperm. PSA is a protein normally made in the prostate gland in ductal cells. These cells make some of the semen that comes out of the penis during sexual climax (orgasm). PSA helps to keep the semen liquid.

Three main conditions with elevated PSA

In three main prostate conditions affecting men's health PSA leaks out of prostate tissue into the bloodstream and can be measured by a PSA test. These three conditions which can affect PSA:

  • Prostatitis and Lower Urinary Tract symptoms (LUTS) can elevate PSA
  • BPH (benign hypertrophy or enlargment of the prostate) can elevate PSA
  • Prostate cancer (PCa) often elevates PSA -- but not always. Some of the most aggressive types of prostate cancer do NOT make or "leak" high levels of PSA.

Prostatitis and BPH are much commoner than prostate cancer.

The fact that non-cancerous conditions can elevate PSA while some aggressive cancers do not elevate PSA makes the test an instrument requiring skilled medical use.

Why not wait for signs or symptoms of prostate cancer?

Early stage prostate cancer usually has no symptoms. Even metastatic disease may exist without causing symptoms or signs.

BBC view of prostate cancer detectionWhen symptoms do occur, they may include any of the following: dull pain in the lower pelvic area; frequent urination; problems with urination such as inability, pain, burning, weakened urine flow; blood in the urine or semen; painful ejaculation; general pain in the lower back, hips or upper thighs; loss of appetite and/or weight; and persistent bone pain.

By the time prostate cancer causes any of these symptoms the tumor is quite far advanced. Although a number of treatments are available for advanced prostate cancer, there is no cure.

NOTE: Several of the symptoms listed above can be caused by non-cancerous conditions.

Prostatitis and LUTS may cause discomfort, fever, and/or lower back pain. Even a young man in his 20s is likely to go to a doctor for relief from such symptoms. Often a round of antibiotics will solve the problem.

Men with BPH generally notice changes in urination like hesitant stream, urgency, nighttime frequency. These changes are bothersome. Most men with BPH who visit a doctor will mention this bother. They can then be advised of medications and procedures to help and be advised that neglecting BPH can lead to conditions like kidney failure.

How is the PSA test done?

Blood is drawn from the arm by a fine needle. This can be done by a nurse, phlebotomist (a nurse trained in blood draws) or doctor. The blood is sent to a laboratory on or off the premises. The patient should receive a copy of the written record of the results. File the record for comparison with tests later on.

The PSA test was originally approved by the FDA in 1986 to aid in the care of patients who already had been diagnosed with prostate cancer. A few years later, in 1994, the FDA approved the PSA test as the first blood test to help detect prostate cancer.

Since the introduction of the PSA test, deaths from prostate cancer have fallen.

"This test -- used with other procedures -- can help detect those men at risk for prostate cancer early on when more treatment options are available," said FDA Commissioner David A. Kessler, M.D in 2003. "But for the test to help, men must be aware of the importance of early check ups and get them on a regular basis."

The PSA test is used for purposes of prostate cancer detection along with a digital rectal exam (DRE). The test should always be given before the digital exam. Touching the prostate may elevate PSA level.

Although it is called "prostate specific," the antigen measured by this test is not specific for prostate cancer. As outlined above, other changes in the prostate gland can cause the PSA to shoot up. In addition to prostatitis and BPH, these events may lead to temporary rise in PSA:

Today various brands of ultra-sensitive PSA test are available to detect extremely low levels of PSA. These ultra-sensitive brands are typically used to test for recurrence of prostate cancer in men who have had surgery, radiotherapy or hormone therapy as a primary or seconday treatment.

Should you take a PSA test and if so starting at what age?

Martin I. Resnick, M.D., president of the American Urological Association, said in July 2003: "Prior experience has indicated that earlier diagnosis of localized prostate cancer can increase the likelihood of curable disease. Prior to the use of the PSA test, tumors were found mostly in advanced – and less treatable – stages, giving patients far fewer options for treatment."

In the past 20 years in the USA - since the introduction of the PSA test - deaths from prostate cancer have fallen by one third. (Centers for Disease Control, CDC).

African American men continue to have higher rates or prostate cancer and death from prostate cancer than other US men. But "Among all racial and ethnic groups, prostate cancer death rates were lower in 1999 than they were in 1990."(CDC).

In the UK and Europe, prostate cancer deaths fell significantly over the last decade, largely because of the use of hormonal treatment and early detection, scientists say. Data presented to the European Cancer Conference in Copenhagen, Denmark, showed deaths fell 20% from 1990 to 2000.

By 1998-1999, US mortality for prostate cancer were the lowest since 1950 in white men. And among black men, death rates in 1999 were the lowest since 1969 when those rates were first recorded. The record low rate for black men was seen in men age 50-69 years.

In 2003 the American Cancer Society (ACS) reported: Prostate Cancer Deaths Down; Possible Link To PSA Test.

"The death rate from prostate cancer is at an all-time low for both white and black Americans -- and a new study suggests that a primary reason may be increased use of the PSA blood test (prostate specific antigen test) to find prostate cancer early."

In 2005, a Harvard study found that men who have a yearly PSA test are nearly three times less likely to die from prostate cancer than those who don't have annual screenings.

Unfortunately, curable disease does not guarantee treatment without side effects. And treatment may fail, even when the cancer appears to be caught at an early stage.

But you will be spared the side-effects, disabilities and suffering of deadly, metastatic prostate cancer.

Biopsy may find a tiny amount of non-lethal prostate cancer. If this happens, depending on your age, changes in your diet and exercise plan may be enough to ensure that a small lesion never becomes a threat to your health and life. You will need a good urologist to keep you under regular observation. A recent study found that as time goes on, untreated prostate cancer that starts out non-lethal tends to become more aggressive.

What is a normal PSA level?

On this site we use the term "normal PSA" but do so with a warning. There is no absolute normal.

Just because a blood test shows you have "normal" PSA does not mean you are guaranteed free from prostate cancer. And just because you have "higher than normal" PSA does not necessarily mean you do have anything malignantly wrong with your prostate.

Low level PSA (from 0 - 3.9 nanograms per milliliter of blood) is generally considered normal - because in most men it indicates freedom from prostate cancer or other prostate disease.

PSA levels higher than 3.9 ng/ml can indicate a problem with the prostate, including inflammation, infection, enlargement or cancer.

But 20% of prostate cancers develop while PSA levels are in the 'normal' range.

And, it is important to note, some men without any prostate problems show PSA levels higher than normal.

In fact only about 1 out of 3 men with elevated PSA levels have cancer. Some men can be healthy and well despite an elevated PSA.

At one time, doctors thought biopsy was not necessary unless the PSA rose above 3.9 mg/ml. Then it became evident, some men develop extremely aggressive prostate cancer without producing much PSA. These men, who need urgent attention, can be missed entirely if the doctor waits for a PSA of 4 ng/ml. They may walk around with low PSA until suddenly their "silent" prostate cancer declares itself in symptoms that are running wild.

These men are a small minority of all the men who are diagnosed with prostate cancer. They get lost among the huge numbers of men who have PSA elevated for any reason. A few of them are far below the age at which prostate cancer is normally expected -- in their thirties or early forties. To diagnose these men and to try to save their lives, urologists must watch rate of PSA change (PSA velocity).

Several leading prostate cancer specialists today recommend a baseline PSA test for all men at age 40 and at age 35 for for men at high risk from family history or African American race.

The American Cancer Society, which takes a more conservative position, recommends men to be screened on an annual basis for prostate cancer beginning at age 50 for caucasians, and age 40 for African-Americans or those with a family history.

Still the question is, if you are screened, what threshold or "cut-off" point will your doctor use before recommending further tests such as "free" to total PSA test and ultrasound guided biopsy?

Given this lack of a strict absolute "normal" level, medical professionals have varying opinions on the value of PSA testing. The test itself is not perfect and it carries with it some risks and benefits.

Benefits of the PSA test include:

  • detecting prostate cancer long before any symptoms present themselves
  • early detection before the cancer has spread outside the gland makes treating the cancer easier and offers the only hope for cure
  • the test has contributed to a significant reduction in prostate cancer deaths

Drawbacks of the PSA test include:

  • in approximately 20% of cases, PSA tests show 'normal' PSA levels in men with early prostate cancer (false-positive)
  • the test itself does not distinguish between prostate cancer and other commoner prostate problems like infection (prostatitis) or benign overgrowth of the prostate (benign prostatic hypertrophy, or BPH).
  • 2 out of 3 of those with elevated levels of PSA do not have prostate cancer, so the test may cause undue worry
  • men over the age of 75 may not benefit from the test, as treating prostate cancer in men past age 75 is less likely to lengthen life span

Other tests beyond PSA and before biopsy

Although the PSA test is not foolproof, it is an extremely effective test when used together with digital rectal examination and, when necessary, transrectal ultrasound and biopsy. In addition, PSA-related measurement and newer forms of the PSA test may be used to distinguish between signs of prostate cancer and other conditions.

Your doctor may take into account your PSA velocity, which is how fast your PSA levels go up. If your PSA level was 1.0 last year, and now it's 2.4, your doctor has cause for concern. More frequent testing (and even a biopsy) may be advised.

Your doctor may consider the size of your prostate gland compared to your PSA level. This comparison is called PSA density. Generally, a high PSA level in a man with a small prostate is more disturbing than the same PSA level in a man with a large prostate.

Newer blood tests include the "free" PSA test (fPSA), the "complexed" PSA test (cPSA), the "pro" PSA test (pPSA) and human kallikrein 2 (hK2).

In the PSA 2.0 to 4.0 ng/ml range, these newer tests are used to increase specificity and to avoid unnecessary biopsies.

Measurement of the ratio between percent of free PSA and bound or total PSA in patients with a PSA level between 4 and 10 ng/ml can help tell the difference between cancer and benign disease and so decreases the number of negative biopsies.

Some studies show that complexed PSA is another test more specific than regular PSA and that PSA ratios (fPSA/cPSA) further increase diagnostic accuracy.

Pro prostate specific antigen (pPSA) is a "precursor form" more often found in tumor compared to benign prostate tissues. It is a still more specific serum marker for prostate cancer, which may be useful for early detection in the 2.5-4.0 ng/ml total PSA range.

Researchers at Johns Hopkins say (Urology. Feb. 2003): "In the 2.5 to 4.0 ng/mL total PSA range, 75% of [prostate] cancers can potentially be detected with 59% of unnecessary biopsies being spared using %pPSA; use of %fPSA would result in sparing only 33% of unnecessary biopsies. A large prospective clinical trial is needed to confirm these preliminary findings."

Researchers at Louisiana State Health Sciences Center (Prostate Cancer Prostatic Dis. 2004 Mar 9) say "percent free PSA offered the best performance and highest specificity in prostate cancer detection in African-American males over the entire range of tPSA. hK2/fPSA may offer modest improvement in the tPSA range of 4.0-10 ng/ml."



Prostate Cancer Treatment Guidelines for Patients
Version III, October 2002 The national Comprehensive Cancer Network

Cáncer de la próstata
Guías de la NCCN para el tratamiento de los pacientes
Transferencia directa aquí


This page made by J. Strax, last edited April 14, 2006.

Information on this website is not intended as medical advice nor to be taken as such. Consult qualified physicians specializing in the treatment of prostate cancer. Neither the editors nor the publisher accepts any responsibility for the accuracy of the information or consequences from the use or misuse of the information contained on this website.

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