The prostate-specific antigen (PSA) blood test is a screening test that measures the amount of prostate-specific antigen (PSA) in a man’s blood. PSA is a chemical made by the prostate, a sex gland located near the bladder in males that produces some of the seminal fluid that bathes sperm cells. Although the amount of PSA in a man’s blood usually increases with age, higher-than-normal PSA levels can be one clue that cancer has developed within the gland. However, high levels of PSA also can be found in other conditions that are noncancerous, including prostatitis (inflammation of the prostate) and benign prostatic hyperplasia, or BPH, (an enlargement of the prostate which affects many older men).
The use of PSA testing to screen for prostate cancer is controversial. Many doctors fear that if PSA is overused, some men will be diagnosed and treated for cancers that have little potential to cause harm. Many men develop prostate cancers that never spread and never cause any problems. If screening is not performed, these cancers might never be detected or they might be found only if an autopsy is performed when a man dies from some other cause. Unfortunately, there is no reliable way of determining in advance which cancers are dangerous until it’s too late
Imagine the following example: An older man develops a cancer that is not destined to spread or cause problems. If a PSA test is performed and it is abnormal, a biopsy would be recommended. If the biopsy shows cancer that has not spread outside the prostate gland, the man must now decide with his physician whether to undergo treatment, such as surgical removal of the prostate gland or radiation therapy. These treatments can have significant side effects and complications. However, there is no way for the man or his physician to know that his cancer will never spread or cause him any problems. Thus, he may choose to undergo aggressive treatment even though such treatment is not needed. If he had not had his PSA tested, he never would have ended up in this position.
Routine use of the PSA test began in the late 1980s. However, some health experts believe that the current use of the PSA test identifies too many men who have abnormal PSA levels but do not have prostate cancer. To refine the test, some experts suggest using one of the following modifications:
- PSA density — dividing the PSA number by the volume of the prostate, as measured by a transrectal ultrasound (TRUS) test
- PSA velocity — a measure of how fast the PSA level is rising over time
- Free-PSA ratio — a measure of how much PSA circulates alone in the blood compared to the amount of PSA bound to other blood chemicals.
For this reason, most groups that make recommendations about cancer screening do not recommend routine PSA testing. Instead, they suggest that physicians should discuss the risks and benefits of prostate-cancer screening with male patients whose age or other factors put them at risk of prostate cancer.
PSA is used as a screening test for cancer of the prostate. In men who have been diagnosed with prostate cancer, PSA is measured to determine whether the cancer is growing or shrinking. Currently, the question of whether or not to perform screening tests for prostate cancer remains controversial.
The National Cancer Institute and the U.S. Preventative Services Task Force recommend screening for prostate cancer with either the PSA test or the digital rectal exam (DRE).
The American College of Physicians-American Society of Internal Medicine recommends that physicians and patients discuss the risks and benefits of prostate-cancer screening and make an individualized decision.
Both the American Cancer Society and the American Urological Association recommend that men should be given the option of undergoing an annual PSA test and DRE beginning at age 50. Both of these tests may be recommended earlier, beginning at age 40 or 45, for men who have an increased risk of prostate cancer. This includes African-American men, who have a 70-percent higher rate of prostate cancer than white men.
Other men who might benefit from earlier PSA testing include men who have a father or brother who was diagnosed with prostate cancer. In men who already have been treated for prostate cancer, the PSA test can give an early warning that cancer has returned.
Ejaculation can cause a brief elevation of your PSA, so you should abstain from sexual activity for at least 48 hours prior to having your PSA level tested. Since blood for your PSA test probably will be taken from your arm, wear a shirt or sweater with sleeves that roll up easily. If you recently have had cystoscopy, needle biopsy or rectal exam of the prostate, let your doctor know so you can schedule your PSA test at another time. Those exams can elevate your PSA level. Both cystoscopy and needle biopsy can raise PSA levels for a few weeks, which may make it harder to interpret your PSA-test result. PSA testing also should not be performed until several weeks after successful treatment of a urinary-tract infection.
Blood for a PSA test usually is drawn from your arm, usually from the area inside the crook of your elbow. The area from which blood will be taken will be cleaned with an alcohol swab, and a sterile needle will be used to draw a few ounces of blood into a vacuum tube. The puncture site will be covered with a small gauze or bandage.
In a few days, call your doctor for your PSA test results. If your result is abnormal, your doctor may recommend further blood tests or additional testing, such as a prostate ultrasound or a biopsy of the prostate.
Having your blood drawn is a simple procedure and there are few, if any, risks. However, when used as a screening test, PSA does have some risks, including:
- A risk that your PSA will be elevated falsely and that you will need to undergo further testing, such as a prostate biopsy. Keep in mind that as many as two-thirds of men with an elevated PSA level do not have prostate cancer. However, many men who are told that their PSA test is abnormal will have some anxiety until final results are available.
- A risk that you will be diagnosed with prostate cancer, and develop significant side effects from treatment that may or may not have been necessary.
- A risk that your PSA level will be normal even if you do have prostate cancer.
Be sure to discuss with your doctor these risks, as well as the benefits, of PSA testing before you have your blood drawn.
When To Call A Professional
Call your doctor if blood continues to ooze from the needle puncture site, or if the site becomes red, swollen or painful.
American Cancer Society (ACS)1599 Clifton Rd., NE Atlanta, GA 30329-4251 Toll-Free: (800) 227-2345
National Cancer Institute (NCI)Building 31Room 10A0331 Center Dr., MSC 2580Bethesda, MD 20892-2580Phone: (301) 435-3848Toll-Free: (800) 422-6237