Prostate Exams & Tests

What type of exam is used to detect prostate cancer?
Your health care provider may feel for any unusual lumps or growths on the prostate by pressing on it or using a gloved finger inside the rectum (digital rectal exam or DRE). Your health care provider may also order a blood test. This blood test measures the level of prostate-specific antigen (PSA), a protein that is produced by the prostate. Higher than expected levels of PSA may mean that a tumor is present. However, high PSA levels may also be caused by an infection or an enlarged prostate. Talk with your health care provider about the tests that are right for you.

The PSA Blood Test
PSA (prostate-specific antigen) is a substance made by the normal prostate gland. Although PSA is mostly found in semen, a small amount is also found in the blood. Most men have levels under 4 ng/mL (nanograms per milliliter) of blood. Prostate cancer can cause the level to go up. If your level is between 4 and 10, you have about a 1 in 4 chance of having prostate cancer. If it is above 10, your chance is over 50% and goes up as the PSA level goes up. But some men with a PSA below 4 can also have prostate cancer.

Factors other than cancer can also cause the PSA level to go up, including having BPH or an infection in the prostate, taking certain drugs, and getting older. Men with a high PSA will need further tests to find out if they actually have cancer.

There are a number of new types of PSA tests that might help to show whether a man needs more testing or not. Not all doctors agree on how to use these new PSA tests. You should talk to your doctor about your cancer risk and any tests that you are having.

There is no question that the PSA test can help spot prostate cancer. But it can’t tell how dangerous the cancer is. The problem is that some prostate cancers are slow growing and may never cause problems. But because of a high PSA level, many men will be found to have prostate cancer that would never lead to their death. Yet they are being treated with either surgery or radiation because they are uncomfortable not having treatment. Doctors and patients are still struggling to decide who should receive treatment and who can be followed without treatment.

The PSA test is also useful after prostate cancer has been found. It can be used along with other results to help decide which types of treatment might be helpful. A very high PSA level might mean that the cancer has spread beyond the prostate. Some forms of treatment are not as useful for cancer that has spread to the lymph nodes or other organs. The PSA test can also be used to help show if treatment is working or if cancer has come back after treatment.

If prostate cancer has spread outside of the prostate or if it has come back after treatment, the way PSA is used changes. The PSA value does not tell whether a person will have symptoms or not or how long he will live. Many men with a high PSA feel just fine. Other people have low values but they have symptoms. With advanced disease, the way the PSA value is changing may be more important than the number alone.

Digital Rectal Exam (DRE)
To do the DRE the doctor inserts a gloved, lubricated finger into the rectum to feel for any irregular or firm areas that might be cancer. The prostate gland is next to the rectum, and most cancers begin in the part of the gland that can be reached by a rectal exam. While it is uncomfortable, the exam isn’t painful and takes only a short time.

The 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. For this reason, ACS guidelines recommend that when prostate cancer screening is done, both the DRE and the PSA should be used. The DRE is also used once a man is known to have prostate cancer. It can help tell whether the cancer has spread beyond his prostate gland. It can also be used to find cancer that has come back after treatment.