Screening refers to testing to find a disease such as cancer in people who do not have symptoms of that disease. For some types of cancer, screening can help find cancers in an early stage when they are more easily cured. Prostate cancer can often be found early by testing the amount of prostate-specific antigen (PSA) in the blood. Another way to find prostate cancer is the digital rectal exam (DRE), in which your doctor inserts a gloved finger into the rectum to feel the prostate gland. If the results of either one of these tests are abnormal, further testing is needed to see if there is a cancer. If you have routine yearly exams and either one of these test results becomes abnormal, then any cancer you might have has likely been found at an early, more treatable stage. The DRE and the PSA test are both discussed in more detail later in this document.

Since the use of early detection tests for prostate cancer became fairly common (about 1990), the prostate cancer death rate has dropped. But it isn't yet clear if this drop is a direct result of screening or caused by something else, like improvements in treatment.

Unfortunately, there are limits to the current screening methods. Neither the PSA test nor the DRE is 100% accurate. Abnormal results of these tests don't always mean that cancer is present, and normal results don't always mean that there is no cancer. Uncertain or false test results could cause confusion and anxiety. Some men might have a prostate biopsy (which carries its own small risks, along with discomfort) when cancer is not present, while others might get a false sense of security from normal test results when cancer is actually present.

There is no question that the PSA test can help spot many prostate cancers early, but another important issue is that it can't tell how dangerous the cancer is. Finding and treating all prostate cancers early may seem like a no-brainer. But some prostate cancers grow so slowly that they would likely never cause problems. Because of an elevated PSA level, some men may be diagnosed with a prostate cancer that they would have never even known about at all. It would never have caused any symptoms or lead to their death. But they may still be treated with either surgery or radiation, either because the doctor can't be sure how aggressive the cancer might be, or because the men are uncomfortable not having any treatment. These treatments can have side effects that seriously affect a man's quality of life. Doctors and patients are still struggling to decide who should receive treatment and who might be able to be followed without being treated right away (an approach called "watchful waiting" or "expectant management").

Studies are under way to try to determine if early detection tests for prostate cancer in large groups of men will lower the prostate cancer death rate. Early results from two large studies haven't offered clear answers.

Interim results from a study done in the United States found that annual screening with PSA and DRE detected more prostate cancers, but it did not lower the death rate from prostate cancer. A European study did find a lower risk of death from prostate cancer with PSA screening (done about once every 4 years), but the researchers estimated that about 1,400 men would need to be screened (and 48 treated) in order to prevent one death from prostate cancer. Neither of these studies has shown that PSA screening helps men live longer (lowered the overall death rate).

Prostate cancer tends to be a slow growing cancer, so the effects of screening in these studies will likely become clearer in the coming years. Both of these studies are being continued to see if longer follow-up will provide more definitive results.

The American Cancer Society (ACS) feels that available evidence does not support routine screening for all men. The ACS recommendation (see below) is that men should make informed decisions based on available information, discussion with their doctor, and their personal perspectives on the benefits and side effects of screening and treatment.

Until more information is available, whether you have the tests is something for you and your doctor to decide. There are many factors to take into account, including your age and health. If you are young and develop prostate cancer, it will probably shorten your life if it is not caught early. If you are older or in poor health, then prostate cancer may never become a major problem because it is generally a slow-growing cancer.

ACS recommendations for the early detection of prostate cancer

The American Cancer Society does not support routine testing for prostate cancer at this time. The ACS does believe that health care professionals should discuss the potential benefits and limitations of prostate cancer early detection testing with men before any testing begins. This discussion should include an offer for testing with the prostate-specific antigen (PSA) blood test and digital rectal exam (DRE) yearly, beginning at age 50, to men who are at average risk of prostate cancer and have at least a 10-year life expectancy. Following this discussion, those men who favor testing should be tested. Men should actively take part in this decision by learning about prostate cancer and the pros and cons of early detection and treatment of prostate cancer.

This discussion should take place starting at age 45 for men at high risk of developing prostate cancer. This includes African American men and men who have a first-degree relative (father, brother, or son) diagnosed with prostate cancer at an early age (younger than age 65).

This discussion should take place at age 40 for men at even higher risk (those with several first-degree relatives who had prostate cancer at an early age).

If, after this discussion, a man asks his health care professional to make the decision for him, he should be tested (unless there is a specific reason not to test).

Recommendations of other organizations

No major scientific or medical organizations, including the American Cancer Society (ACS), American Urological Association (AUA), US Preventive Services Task Force (USPSTF), American College of Physicians (ACP), National Cancer Institute (NCI), American Academy of Family Physicians (AAFP), and American College of Preventive Medicine (ACPM) support routine testing for prostate cancer at this time.

These organizations (the ACS, AUA, ACP, NCI, AAFP, ACPM, and the USPSTF) recommend that health care professionals discuss the possible benefits, side effects, and questions about early prostate cancer detection and treatment so that men can make informed decisions taking into account their own situation and risk.

The USPSTF published an update of its recommendations in 2008. It concluded that the risks of screening for prostate cancer outweigh the benefits for men age 75 years or older (as well as for men whose life expectancy is 10 years or fewer). For these men, the USPSTF is now recommending against prostate cancer screening. For men younger than 75 years old who have a life expectancy more than 10 years, the USPSTF indicated that the studies completed so far still do not provide enough evidence to know whether the benefits of testing for early prostate cancer outweigh the possible risks. For men in this age group, the USPSTF continues to recommend that health care providers discuss the potential benefits and known harms of PSA screening and then allow the patients' personal preferences to guide the decision of whether to order the test.

In addition, the American Cancer Society and the American Urological Association recommend that health care professionals offer the option of testing for early detection of prostate cancer to all men who are at least 50 years old (or younger if at higher risk).

Prostate-specific antigen (PSA) blood test

Prostate-specific antigen (PSA) is a substance made by cells in the prostate gland (it is made by normal cells and cancer cells). Although PSA is mostly found in semen, a small amount is also found in the blood. Most healthy men have levels under 4 nanograms per milliliter (ng/mL) of blood. The chance of having prostate cancer goes up as the PSA level goes up.

When prostate cancer develops, the PSA level usually goes above 4. Still, a level below 4 does not mean that cancer isn't present -- about 15% of men with a PSA below 4 will have prostate cancer on biopsy. Men with a PSA level in the borderline range between 4 and 10, have about a 1 in 4 chance of having prostate cancer. If the PSA is more than 10, the chance of having prostate cancer is over 50%.

The PSA level can also be increased by things other than prostate cancer, such as:

• benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the prostate that many men get as they grow older

• age: PSA levels will also normally go up slowly as you get older, even if you have no prostate abnormality.

• prostatitis, an infection or inflammation of the prostate gland

• ejaculation can cause the PSA to go up for a short time, and then go down again. This is why some doctors will suggest that men abstain from ejaculation for 2 days before testing.

Some things cause PSA levels to go down (even when cancer is present), including:

• Certain medicines used to treat BPH or urinary symptoms, such as finasteride (Proscar or Propecia) or dutasteride (Avodart). You should tell your doctor if you are taking these medicines, because they may lower PSA levels and require the doctor to adjust the reading.

• Some herbal mixtures that are sold as dietary supplements "for prostate health" may also mask a high PSA level. This is why it is important to let your doctor know if you are taking any type of supplement. Saw palmetto (an herb used by some men to treat BPH) does not seem to interfere with the measurement of PSA.

• Obesity: Obese men tend to have lower PSA levels

If your PSA level is high, your doctor may advise a prostate biopsy to find out if you have cancer (see the section, "How is prostate cancer diagnosed?"). Some doctors may consider using newer types of PSA tests (discussed below) to help determine if you need a prostate biopsy, but not all doctors agree on how to use these other PSA tests. If your PSA test result is not normal, ask your doctor to discuss your cancer risk and your need for further tests.

Percent-free PSA

PSA occurs in 2 major forms in the blood. One form is attached to blood proteins while the other circulates free (unattached). The percent-free PSA (fPSA) is the ratio of how much PSA circulates free compared to the total PSA level. The percentage of free PSA is lower in men who have prostate cancer than in men who do not.

This test is sometimes used to help decide if you should have a prostate biopsy if your PSA results are in the borderline range (between 4 and 10). A lower percent-free PSA means that your likelihood of having prostate cancer is higher and you should probably have a biopsy. Many doctors recommend biopsies for men whose percent-free PSA is 10% or less, and advise that men consider a biopsy if it is between 10% and 25%. Using these cutoffs detects most cancers while helping some men to avoid unnecessary prostate biopsies. This test is widely used, but not all doctors agree that 25% is the best cutoff point to decide on a biopsy.

A newer test, known as complexed PSA, measures the amount of PSA that is attached to other proteins. This test is described in more detail in the section, "What's new in prostate cancer research and treatment?"

PSA velocity

The PSA velocity is not a separate test. It is a measure of how fast the PSA rises over time. Even when the total PSA value isn't over 4, a high PSA velocity suggests that cancer may be present and a biopsy should be considered. For example, if your PSA was 1.7 on one test, and then a year later it was 3.8, this rapid rise may be cause for concern.

This can be useful if you are having the PSA test every year. For men whose initial PSA value is less than 4, a PSA velocity of 0.35 (ng/mL) per year or greater (for example, if values went from 2 to 2.4 to 2.8 over the course of 2 years) may be cause for concern. For men whose PSA value is between 4 and 10, a biopsy should be more strongly considered if it goes up faster than 0.75 (ng/mL) per year (for example, if values went from 4 to 4.8 to 5.6 over the course of 2 years). Most doctors believe that PSA levels should be measured on at least 3 occasions over a period of at least 18 months in order to get an accurate PSA velocity.

PSA density

PSA levels are higher in men with larger prostate glands. The PSA density (PSAD) is sometimes used for men with large prostate glands to try to adjust for this. The doctor measures the volume (size) of the prostate gland with transrectal ultrasound (discussed below) and divides the PSA number by the prostate volume. A higher PSA density (PSAD) indicates greater likelihood of cancer. PSA density has not been shown to be that useful. The percent-free PSA test has so far been shown to be more accurate.

Age-specific PSA ranges

PSA levels are normally higher in older men than in younger men, even when there is no cancer. A PSA result within the borderline range might be very worrisome in a 50-year-old man but cause less concern in an 80-year-old man. For this reason, some doctors have suggested comparing PSA results with results from other men of the same age.

But because the usefulness of age-specific PSA ranges is not well proven, most doctors and professional organizations (as well as the makers of the PSA tests) do not recommend their use at this time.

Using the PSA blood test after prostate cancer diagnosis

The PSA test is used mainly to detect prostate cancer early, but it is useful in other situations:

• In men diagnosed with prostate cancer, the PSA test can be used together with clinical exam results and tumor grade (from the biopsy) to help decide if further tests (such as CT scans or bone scans) are needed.

• It can help tell whether your cancer is still confined to the prostate gland. If your PSA level is very high, your cancer has likely spread beyond the prostate. This may affect your treatment options, since some forms of therapy (such as surgery and radiation) are not likely to be helpful if the cancer has spread to the lymph nodes, bones, or other organs.

• After surgery or radiation treatment, the PSA level can be watched to help determine if the treatment was successful. PSA levels normally fall to very low levels if the treatment removed or destroyed all of the prostate cells. A rising PSA level (especially after surgery) likely means that prostate cancer cells are present and your cancer has come back.

• If you choose a "watchful waiting" approach to treatment, the PSA level can be used to help decide whether the cancer is growing and if active treatment should be considered.

• During hormonal therapy or chemotherapy, the PSA level can help indicate how well the treatment is working or when it may be time to try a different form of treatment.

If prostate cancer has come back (recurred) after treatment, or if it has spread outside of the prostate (metastatic disease), the actual PSA number is probably not as important as whether it changes. The PSA number does not predict whether or not a person will have symptoms or how long he will live. Many people have very high PSA values and feel just fine. Other people have low values and have symptoms. With advanced disease, it may be more important to look at the way the PSA level is changing rather than the actual number.

Digital rectal exam (DRE)

For a digital rectal exam (DRE), a doctor inserts a gloved, lubricated finger into the rectum to feel for any bumps or hard areas on the prostate that might be cancer. The prostate gland is found just in front of the rectum, and most cancers begin in the back part of the gland, which can be felt during a rectal exam. This exam is uncomfortable, but it isn't painful and only takes a short time.

DRE is less effective than the PSA blood test in finding prostate cancer, but it can sometimes find cancers in men with normal PSA levels. This is why the American Cancer Society guidelines recommend that when prostate cancer screening is done, both the DRE and PSA blood test should be used.

The DRE can also be used once a man is known to have prostate cancer to try to determine if it may have spread to nearby tissues and to detect cancer that has come back after treatment.

Transrectal ultrasound (TRUS)

Transrectal ultrasound (TRUS) uses sound waves to make an image of the prostate on a video screen. For this test, a small probe that gives off sound waves is placed in the rectum. The sound waves enter the prostate and create echoes that are picked up by the probe. A computer turns the pattern of echoes into a black and white image of the prostate.

The procedure takes only a few minutes and is done in a doctor's office or outpatient clinic. You will feel some pressure when the TRUS probe is placed in your rectum, but it is usually not painful.

TRUS is usually not recommended as a routine test by itself to detect prostate cancer because it doesn't often show early cancer. Instead, it is most commonly used during a prostate biopsy (described in the next section). TRUS is used to guide the biopsy needles into the right area of the prostate.

TRUS is useful in other situations as well. It can be used to measure the size of the prostate gland, which can help determine the PSA density and may also affect which treatment options a man has. It is also used as a guide during some forms of treatment such as cryosurgery.

Signs and symptoms of prostate cancer

Early prostate cancer usually causes no symptoms and is most often found by a PSA test and/or DRE. Some advanced prostate cancers can slow or weaken your urinary stream or make you need to urinate more often. But non-cancerous diseases of the prostate, such as BPH (benign prostatic hyperplasia) cause these symptoms more often.

If the prostate cancer is advanced, you might have blood in your urine (hematuria) or trouble getting an erection (impotence). Advanced prostate cancer commonly spreads to the bones, which can cause pain in the hips, spine, ribs, or other areas. Cancer that has spread to the spine can also press on the spinal nerves, which can result in weakness or numbness in the legs or feet, or even loss of bladder or bowel control.

Other diseases can also cause many of these same symptoms. It is important to tell your doctor if you have any of these problems so that the cause can be found and treated.

Last Medical Review: 07/30/2009
Last Revised: 07/30/2009