What is the protein-specific antigen (PSA)?

PSA is an enzyme produced by the prostate. The primary role of PSA is to liquefy semen in order to facilitate the movement of sperm. PSA is present primarily in the semen, but it can also be found in the blood or bound to two proteins: alpha 1 antichymotrypsin (ACT) and alpha-macroglobulin (AMG).

What is a PSA test?

A PSA test measures the amount of free and bound PSA in the blood. For this test, a blood sample is analyzed in the lab. The level of PSA in the blood is usually measured in nanograms of PSA per milliliter of blood (ng/mL). Combined together, the digital rectal exam (DRE) and the PSA test are methods used for the early detection of prostate cancer.

Who should have a PSA test?

If you are over 50 years old, you should consider having a PSA test done. If you are under 50 years old but at a higher risk for prostate cancer, a screening strategy may be recommended, beginning at 40 or 45 years old. Discuss the advantages and risks of the PSA test with your doctor.

What can I learn from a PSA test?

A raised PSA level can be a sign of one of the following problems:

• An enlarged prostate (benign prostatic hyperplasia)
• Inflammation or infection of the prostate (prostatitis)
• Prostate cancer

Many men that have a high PSA level do not have prostate cancer. On the other hand, some men with prostate cancer have a normal PSA level. Your doctor will take into consideration other factors, such as family history, and will have you undergo other tests, such as a digital rectal exam, before deciding whether you should consult a specialist.

What can affect my PSA level?

PSA is produced by healthy cells in the prostate. This is why it’s normal to find a small amount of PSA in the blood of every man. However, the following factors can increase the PSA level in your blood:

• Your age.
• Your racial origin.
• An enlarged prostate (BPH).
• Treatment will be prescribed and you will need to wait until the inflammation disappears, before retaking a PSA test.
• Urinary infection. Treatment will be prescribed and you will need to wait four to six weeks, the time it takes for the infection to clear up, before retaking a PSA test.
• Vigorous exercise, like biking, in the 48 hours before a PSA test.
• Anal sex or prostate stimulation. It is better to avoid these activities in the week before a PSA test.
• A prostate biopsy in the six weeks before a PSA test.
• A procedure or an operation on the bladder or prostate, or the use of a catheter. It is better to wait up to six weeks after such a procedure before having a PSA test.
• Ejaculation in the 48 hours before a PSA test, although questionable.

You should also let your doctor know what medication you are taking as some medication can affect your PSA level. A DRE just before a PSA test does not impact results.

What do my PSA test results mean?

Your PSA test results alone will not tell you whether you have prostate cancer. Other factors must also be taken into consideration. It is important to keep in mind that it is normal for a healthy man to have a small amount of PSA in his blood and that this amount will increase with a man’s age as the prostate naturally gets larger and produces more PSA. The following PSA ng/mL levels are considered to be “normal”:

• Less than 50 years: 0.0 to 2.5
• 50-59 years: 0.0 to 3.5
• 60-69 years: 0.0 to 4.5
• Over 70 years: 0.0 to 6.5

Normal PSA levels mean that you probably won’t need to take any other tests. However, you may need to undergo another PSA test in the future.

High PSA levels for your age may indicate the presence of prostate cancer. However, you could also have a non-cancerous condition such as benign prostatic hyperplasia or prostatitis. Other tests are necessary to determine the exact cause for the increase in your PSA level.

Very high PSA levels (over 100 ng/mL) usually indicate prostate cancer, but other tests are needed to confirm the diagnosis.

Other PSA level analyses

Serial PSA testing. According to your first PSA test, you may be advised to undergo regular PSA testing. This method allows one to monitor the fluctuation of your PSA level over time. We know that PSA levels of all men gradually increase with age, but having cancer is often coupled with a rapid PSA level increase. Periodic monitoring of PSA levels is also used to assess your response to cancer treatments.

Free PSA testing. PSA circulates in the blood in two forms: complexed (attached to other proteins) and free. The current PSA test measures total PSA, that is to say, the total sum of both forms of PSA. However, another test measures only free PSA. The free-to-total PSA ratio is often lower in men with prostate cancer than in those who have a benign prostate condition.

PSA density (PSAD) measurement. The larger the prostate, measured using a transrectal ultrasound, the higher we expect PSA levels to be. A “normal” PSA level can be different depending on the size of the prostate. The PSA density thus determines the PSA level with respect to prostate size. High PSA density (high PSA/size ratio) often indicates an increased risk for cancer.

Nomograms. A nomogram is a rating scale based on age, ethnicity, family history, urinary symptoms, DRE results, and biopsy results. It is used to predict, with certainty, the risk and aggressivity of prostate cancer.

It is important to weigh the pros and cons of the PSA test. What might be an advantage for one man may not necessarily be the case for all men.

Advantages

• A PSA test can help detect prostate cancer before you show any symptoms.
• A PSA test can help detect an aggressive cancer at an early stage in its development and allows for treatment before the cancer spreads.
• A non-aggressive cancer may not need treatment. Regular check-ups and PSA tests can allow you to delay treatment and its associated side effects while keeping an eye on the cancer’s development.
• Regular PSA tests can be helpful for men at high risk of prostate cancer by allowing for the early detection of cancer.

Limitations

• An elevated PSA level does not necessarily mean you have prostate cancer. Around 3/4 of men with a raised PSA level do not have prostate cancer (false‑positive result).
• An elevated PSA may require you to undergo other tests that may pose certain risks. For example, a biopsy can cause pain, infection, and bleeding.
• The PSA test can have a false-negative result. About 2% of men with an aggressive prostate cancer have a normal PSA level.
• A slow-growing cancer could have no impact on your life, but the fact that you know you have cancer can be worrisome and lead to unnecessary treatment.
• Side effects of a treatment for prostate cancer can affect your daily life. These side effects can include urinary, bowel, and erectile problems.

Before deciding to have a PSA test, ask yourself these questions and discuss them with your doctor, your family, and your friends:

• What are my risks of prostate cancer?
• Would I be reassured if my PSA test results are normal?
• What will I do if my PSA level is high?
• If I am diagnosed with a slow-growing cancer that might not cause me any problems in my lifetime, would I want to undergo a treatment that could have side effects that impact my daily life?

PSA testing during and after treatment

During your treatment, the PSA level is measured periodically to assess the cancer’s response to treatment.

After your treatment, whether it is an operation, radiotherapy, or hormone therapy, your PSA level should decrease and stabilise. Consequently, if your blood tests repeatedly show that your PSA level has significantly increased, the results strongly suggest a recurrence of the disease and may call for additional treatments.