Approximately 1 out of 9 men will develop prostate cancer during their lifetimes. This cancer develops in the prostate gland, a part of the male reproductive system that produces fluid to keep sperm healthy. 

Urologists (doctors who specialize in conditions that affect the urinary and reproductive systems) use a blood test to look for elevated levels of a specific protein that can indicate the onset of prostate cancer. This is called a prostate-specific antigen (PSA) test.

What is a PSA test?

A PSA test is a screening tool for prostate cancer, as well as other noncancerous (benign) conditions like an enlarged prostate that can affect prostate health. It can show if there are higher-than-usual levels of PSA, but it can’t show what condition is causing the increase. Your doctor will order other tests to make a diagnosis. 

Your doctor may order a PSA test to:

• screen for prostate cancer

• see if prostate cancer has returned or spread (metastatic prostate cancer) after treatments

From the community: “As you have stated, PSA of 4 or higher generally is the threshold for looking further with an MRI or biopsy provided one has not been previously shown to have cancer. If you have been previously treated for prostate cancer a lower reading might signal recurrence. Other things can greatly affect PSA. These include BPH, an infection like prostatitis, ejaculation within 48 hours of having the test, cycling, enlarged prostate, and age, to name a few. As you age a "normal" PSA could even be 6 and still be cancer free. PSA is a useful tool but not an exact determination of whether or not one is cancerous, only a biopsy does that… I guess that what I am trying to convey is that there is much more to prostate cancer than PSA.” – Inspire member

How does a PSA test work?

A PSA test requires a simple blood draw. The blood sample goes to a lab, which returns results to your doctor. Men always have small amounts of PSA in their blood. The protein is also found in semen. But a high amount in the blood may indicate a problem.

How should I prepare for a PSA test?

These steps can help ensure the most accurate reading possible: 

• Hold off if you’ve had a urinary tract infection (UTI), catheter, or prostate biopsy. All of these can cause inflammation that raises PSA levels. You should wait at least six weeks before getting tested.

• Don’t ejaculate for 48 hours before testing. The release of semen sends more PSA into the bloodstream, causing the levels to rise temporarily. 

• Don’t participate in vigorous exercise 48 hours before the test. Exercise, especially cycling, which can rub the prostate, can spike PSA levels. 

• Provide your doctor with a list of all medications and supplements you take. Certain medications for an enlarged prostate like  

•  appear to be lower than they truly are. Healthcare providers multiply your PSA reading by a certain number depending on how many years you’ve been taking the drug. 

• Wait after getting a digital rectal exam (DRE). Doctors use DREs (which involve inserting a gloved finger into the rectum) to feel the prostate and determine if it’s enlarged. You shouldn’t get a DRE and a PSA test on the same day. A DRE can stimulate the prostate, causing it to release PSA into the blood.

• Make sure your doctor is aware of any enlarged prostate treatments. A transurethral resection of the prostate (TURP) removes all but the outer part of the prostate gland. Laser therapy also destroys prostate tissue. Because there’s less tissue, PSA readings may be lower and inaccurately indicate that there isn’t a problem.

• Alert your doctor to any liver problems. Cirrhosis of the liver and liver fibrosis (scar tissue in the liver) can lower PSA levels.

From the community: “The only advice I’ve had from doctors is to avoid sexual activity for several days before taking a test. A number states allow inexpensive PSA tests that can be ordered up online ...in event you want to monitor more often. Also since your last PSA went down I suspect you are not in any immediate trouble.” – Inspire member

What do PSA test results mean?

PSA in the blood is measured in nanograms per milliliter (ng/mL). While there isn’t a designated number that definitively indicates prostate cancer, a higher reading generally means a higher probability of cancer. 

For instance:

• A result of 10 ng/mL or higher indicates a 50% chance of prostate cancer. But you have the same chance of having a noncancerous condition.  

• Levels between 4 ng/mL and 10 ng/mL are considered borderline. There’s a 25% chance of prostate cancer. 

• PSA levels below 4 ng/mL are cancerous about 15% of the time.

What happens after a PSA test?

Certain conditions, procedures, and activities can affect PSA levels. And labs use different assay tests to get readings, which means results on the same blood sample can vary from lab to lab. It’s important that the same lab receives your blood sample and performs the PSA test.

It’s normal for PSA levels to fluctuate, so you shouldn’t panic if you get a high reading on one test. Your doctor may recommend getting retested in another three months or longer. For 1 in 4 men, follow-up tests return lower results.

If your results are high, you may get an MRI or a transrectal ultrasound (TRUS). These imaging scans provide detailed pictures of the prostate to help identify abnormalities like prostate stones, abscesses, gland enlargement, or cancer. 

Like a PSA test, imaging scans can identify potential problems, but they can’t pinpoint cancer as the cause. For a cancer diagnosis, you’ll need a core needle biopsy procedure. 

This procedure involves taking small samples (cores) of tissue from the prostate gland through a thin, hollow needle inserted into the numbed area. A lab pathologist examines the biopsy samples for cancer cells. A biopsy can diagnose prostate cancer and identify the prostate cancer stage.

From the community: “I have had 4 different laratories for PSA and they do differ. My clincal trial coordinator puts value only on changes made in PSA within the same labratory.” – Inspire member

What if I have prostate cancer?

Prostate cancer is typically a slow-growing disease. Many men don’t actively need treatment. Based on their doctor’s recommendation, they may take an active surveillance or watchful waiting approach. 

Treatments for prostate cancer — when needed — include:

• radiation therapy like brachytherapy (radioactive pellets implanted into the gland)

• systemic therapies like chemotherapy or targeted therapies for metastatic prostate cancer

• surgery (prostatectomy) to remove the diseased gland

Sources

• Key statistics for prostate cancer. American Cancer Society. January 2021.

• Screening tests for prostate cancer. American Cancer Society. January 2021.

• Levine H. How to get an accurate PSA test for prostate cancer. Consumer Reports. June 19, 2016.

• PSA test. Mayo Clinic. June 2021.

• Why should I avoid sexual activity before a PSA test? National Health Service (UK). December 2019.

• Worthington JF. Make sure your PSA is as accurate as possible. Prostate Cancer Foundation. December 19, 2018.

• Prostate-specific antigen (PSA) blood test. University of California San Francisco (UCSF) Health. January 2020.

Disclaimer

Member comments are lightly edited for length and to remove identifying information but are otherwise reproduced as they appear in the community as part of public posts.

This content is for general informational purposes only and does not necessarily reflect the views and opinions of any organization or individual. The content should not be used as a substitute for professional medical advice, diagnosis, or treatment. Please consult your healthcare provider about any questions you may have regarding a medical condition.