A prostate-specific antigen (PSA) test measures the level of PSA in a man’s blood. PSA is a protein produced by the cells of the prostate, a small gland just below a man’s bladder. PSA circulates through the entire body at low levels at all times.
A PSA test is sensitive and can detect higher than average levels of PSA. High levels of PSA may be associated with prostate cancer before any physical symptoms appear. According to the Centers for Disease Control and Prevention (CDC), prostate cancer is the second most common cancer among men in the United States (CDC, 2012). However, high levels of PSA may also mean you have a noncancerous condition that is increasing PSA levels.
A PSA test alone is not enough for a doctor to make a diagnosis. However, doctors take the result of a PSA test into consideration when trying to decide whether a man’s symptoms and test results are due to cancer or another condition.
PSA tests remain controversial because doctors and experts aren’t sure if the benefits of early detection outweigh the risks of misdiagnosis. It’s also not clear if the screening test actually saves lives. Because the test is very sensitive and can detect increased PSA numbers at low concentrations, it may detect cancer that is so small it would never become life-threatening.
This is called an overdiagnosis—and more men may face complications and risks of side effects from the treatment of a growth than they would if the cancer had been left undiagnosed. It’s doubtful those small cancers would ever cause major symptoms and complications, because prostate cancer, in most—but not all—cases, is a very slow-growing cancer.
PSA levels rise with age, so doctors must use a PSA reference range to determine if a man’s PSA levels are average or troublesome. However, according to the National Cancer Institute (NCI), healthcare providers do not favor these ranges. These ranges may lead to false negatives or delayed diagnoses in as many as 20 percent of men in their sixties, and 60 percent of men in their seventies (NCI, 2012). Your doctor will know if one is right for you.
According to the Centers for Disease Control and Prevention, prostate cancer is the second most common cause of cancer death in American men (CDC, 2012). All men are at risk for the disease, but a few populations are more likely to develop prostate cancer. These include:
- older men
- African-American men
- men with a family history of prostate cancer
The U.S. Food and Drug Administration (FDA) has approved the use of a PSA test along with a digital rectal exam (DRE) to detect prostate cancer in men age 50 and older. Some doctors may use the test in men who are at higher risk for prostate cancer by age 40 or 45. A PSA test is also FDA-approved to monitor the recurrence of prostate cancer (CDC, 2012).
Early detection is an important part of most cancer treatments, and a PSA test may be able to detect the earliest stages of prostate cancer. Other reasons your doctor may order a PSA include:
- to monitor prostate cancer treatment
- to determine what’s causing a physical abnormality on your prostate (your doctor will detect this during a physical exam)
- to help decide when to begin treatment
If your doctor requests that you have a PSA test, make sure that he or she is aware of any prescription or over-the counter medicines, vitamins, or supplements you take. Certain drugs may cause the test results to be falsely low. If your doctor thinks your medication might interfere with the results, he or she may decide to request a different test, or may ask you to avoid taking your medicine for several days so the results will be more accurate.
A sample of your blood will be sent to a laboratory for further examination. To withdraw blood from an artery or vein, a nurse or healthcare provider will insert a needle—most often in your elbow. You may feel a sharp, piercing pain or slight sting as the needle is inserted into the vein.
Once the nurse has collected enough blood for the samples, he or she will remove the needle and hold pressure on the area to stop the bleeding. The nurse will then put an adhesive bandage over the insertion site in the event you still bleed a bit more.
The blood samples will be sent to a laboratory for testing and analysis. Ask your doctor if he or she will follow-up with you regarding your results, or if you should make an appointment to come in and discuss the results.
Drawing blood is considered safe. However, because veins and arteries vary in size and depth, getting a blood sample is not always simple. The healthcare provider who is drawing your blood may have to try several veins in multiple locations on your body before they find one that allows him or her to get enough blood.
Drawing blood also has several other risks. These include:
- a risk of fainting
- excessive bleeding
- feeling light-headed or dizzy
- an infection at the puncture site
- a hematoma (blood collected under the skin) at the puncture site
If your PSA levels are elevated, you will likely need additional tests in order to diagnose the reason for the elevated numbers. Other possible reasons for a rise in PSA include:
- you recently had a catheter tube inserted into your bladder to help drain urine
- you recently had testing done on your bladder or prostate
- you have a urinary tract infection
- you have prostatitis (an inflamed prostate)
- you have an infected prostate
- you have benign prostatic hyperplasia (BPH), or an enlarged prostate
If you have an elevated risk of prostate cancer or your doctor suspects you may have prostate cancer, a PSA test can be used as part of a larger group of tests to detect and diagnose prostate cancer. Other tests you may need include:
- a digital rectal exam
- a free PSA (fPSA)
- repeated PSA tests
- a prostate biopsy