Prostate-specific antigen

Prostate-specific antigen, or PSA, is a protein that the prostate gland produces. A PSA test is a simple test that measures the amount of prostate-specific antigen a man has in his blood. When the prostate gland is healthy, usually very little PSA escapes through the wall of the gland into the blood.

Before the test

Ejaculation can make a man’s PSA temporarily rise, so the doctor may tell you and your loved one to not have sex several days before his test. Be sure to tell the doctor about any medicines or herbal remedies that your loved one is taking, as these can also affect his score.

The doctor will withdraw a blood sample with a needle and send it to a laboratory for analysis. It used to be that a PSA level above 4 ng/mL (which means 4 nanograms per milliliter) was generally considered to be above normal. However, some doctors believed that the “normal” cutoff should be lower, as some men with lower numbers can still have prostate cancer. And men with high levels of prostate-specific antigen may have conditions other than prostate cancer, such as benign prostatic hyperplasia (BPH) and prostatitis.

The American Urological Association (AUA) issued a 2009 update to their Prostate-Specific Antigen Best Practice Statement, which had two major changes from their previous guidelines.

First, they lowered the suggested age for a baseline PSA to 40 in men who wish to be screened, whether a man has any risk factors or not. Second, they no longer recommend using a single PSA test value as a threshold number to determine whether or not a man should have a biopsy. They also advocate that men should have both PSA testing and a digital rectal exam.

The AUA guidelines state that "the decision to proceed to prostate biopsy should be based primarily on PSA, patient age, PSA velocity, PSA density, family history, ethnicity, prior biopsy history and comorbidities."

What does this all mean?

According to the AUA guidelines, there is no longer a "normal" or "abnormal" PSA number. Now doctors are looking to "risk-stratify" men, which is a way of saying that they are trying to determine what a man's individual risk of developing prostate cancer may be. This has been an evolving issue (and more changes may be coming), and is part of a larger debate within the medical community about whether men are being "over-treated" for prostate cancer.

According to the AUA guidelines, if a 40-year-old man gets a baseline PSA test, and his PSA number is >0.7 ng/mL, then he may be at risk for prostate cancer in the future, because the median PSA value for men in their 40s is between 0.6 ng/mL and 0.7 ng/mL.

The guidelines state that an average man older than age 50 who has a normal DRE has about a 10% chance of having biopsy-detectable prostate cancer if his PSA is 0.0 to 2.0 ng/mL. The risk rises to 15-25% if his PSA is 2.0 to 4.0 ng/mL, and 17%-32% if it is 4.0-10.0 ng/mL. If his PSA is above 10.0 ng/mL, the risk is 43%-65%.

The AUA guidelines suggest that men should be informed of the risks and benefits of prostate cancer screening before they have a biopsy.

The American Cancer Society (ACS) also does not support routine testing at this time. Their 2010 guideline suggests that doctors should offer information about testing to men who have no symptoms of prostate cancer beginning at age 50 (for men with average risk and an expected lifespan of at least 10 years) and discuss the benefits and risks of early detection testing. The ACS 2010 guideline states that men at higher risk should receive this information beginning at age 45. This includes African American men and men who have a first-degree relative (father or brother) diagnosed with prostate cancer before age 65. Men at appreciably higher risk should receive this information beginning at age 40. This includes men who have had multiple family members diagnosed with prostate cancer before age 65.

According to the ACS 2010 guideline, asymptomatic men (men who have no symptoms of prostate cancer) who have less than a 10-year life expectancy based on age and health status should not be offered prostate cancer screening.

In the end, the decision is up to you and your loved one! But understand that if your man wants to be tested, he may need to push for it.

Be proactive

When your loved one goes for his yearly annual exam, he should talk to his doctor about whether prostate-specific antigen testing and a digital rectal exam (DRE) are right for him.

If the doctor orders a PSA test, always ask for the test results. Never assume that “no news is good news.”

Understand that having a low PSA score does not always mean that a man does not have prostate cancer, just as having a high number does not always mean that he does have prostate cancer. These tests are not 100% accurate, and results may even vary from one lab to another.

PSA tests after treatment for prostate cancer may be stressful for you and your loved one. You may have fears that the cancer has returned. Take heart in knowing that if this happens, there may be other treatment options to consider.

References:
American Urological Association. Prostate-Specific Antigen Best Practice Statement: 2009 Update. http://www.auanet.org/content/guidelines-and-quality-care/clinical-guidelines/main-reports/psa09.pdf. Accessed May 6, 2009.

The American Cancer Society. Prostate Cancer. http://www.cancer.org. Accessed September 1, 2009.

Vashi AR, Oesterling JE. Percent free prostate-specific antigen: entering a new era in the detection of prostate cancer. Mayo Clin Proc. 1997;72:337-344.

Walsh PC. Guide to Surviving Prostate Cancer. New York, NY: Time Warner Book Group; 2001.