PCA3

At a Glance

Why Get Tested?

To help determine if a repeat prostate biopsy is indicated to help detect prostate cancer

When to Get Tested?

When a healthcare practitioner is considering a repeat prostate biopsy for a man age 50 or older who has had one or more previous negative biopsies

Sample Required?

The first amount of urine collected after a healthcare practitioner performs a digital rectal exam (DRE)

Test Preparation Needed?

None

You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

This Website is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

What is being tested?

The prostate cancer antigen 3 (PCA3) test detects genetic material (messenger RNA (mRNA)) that is produced only by the prostate. The protein PCA3 and its associated mRNA are present at low levels in normal prostate tissue. PCA3 is present in increased amounts (over-expressed) in about 90% of prostate cancers. Prostate specific antigen (PSA) is also produced in increased amounts by prostate cancers but can be increased in a number of benign conditions as well.

This test measures PCA3 mRNA and PSA mRNA in the first urine sample collected following a digital rectal exam (DRE). Laboratories report a score based on the ratio of PCA3 mRNA to PSA mRNA called the PCA3 score.

Prostate cancer is the uncontrolled growth of cells in the prostate, a small gland that encircles the urethra in men. Some men may choose to undergo screening for prostate cancer using a PSA blood test. An increased PSA level is associated with an increased risk of prostate cancer, but PSA can also be increased with benign prostatic hyperplasia (BPH), prostatitis, infection, and a variety of other temporary conditions.

Diagnosis of prostate cancer requires performing a prostate biopsy and identifying cancer cells under the microscope. This biopsy may be done after an increased PSA result and/or an abnormal DRE. The accuracy of biopsies depends on the number of tissue samples and the sites from which they are taken. Since the biopsy takes small tissue samples, and since PSA is not cancer-specific, the initial biopsy is often negative.

A negative initial biopsy may leave the healthcare practitioner questioning whether the patient is truly cancer-free or if the cancer has been missed. Concerns over missing clinically significant cancer may prompt additional biopsies, especially if a repeat PSA is still elevated or has increased. However, each biopsy has potential complications, such as discomfort, blood in the urine (hematuria) or semen, rectal bleeding, difficulty urinating, infection, and in rare cases septicemia, so minimizing the number of biopsies performed is also desirable.

The PCA3 test can help determine if a repeat prostate biopsy would likely be positive and whether a man may avoid an unnecessary repeat biopsy. PCA3 is significantly over-expressed with prostate cancer but (unlike PSA) it is not affected by prostatitis or BPH.

Common Questions

How is the test used?

The PCA3 test is used to help decide whether a repeat prostate biopsy should be performed on a man age 50 or older who has had one or more previous negative biopsies.
When is it ordered?

The test may be ordered when a man has had an elevated PSA blood test and/or abnormal digital rectal exam (DRE) and one or more previous negative prostate biopsies. It may be ordered when another biopsy would normally be recommended and a healthcare practitioner wants to evaluate the likelihood that the repeat biopsy would be positive.
What does the test result mean?

The PCA3 test result is a ratio of PCA3 mRNA to PSA mRNA that is reported as a score. The laboratory report provides a cut-off number at which the score is considered positive.

The PCA3 test does not provide a definitive answer as to whether a man has a cancer or not. Rather, healthcare practitioners consider the test results in conjunction with other laboratory and clinical data to determine the likelihood that a repeat biopsy will be positive.

A PCA3 score that is less than the laboratory's established cutoff is considered negative and is associated with a decreased likelihood of a positive biopsy.

A PCA3 score that is greater than the laboratory's established cutoff is considered positive and is associated with an increased likelihood of a positive biopsy. Some labs provide a range in which PCA3 is considered positive but with a caution about interpreting results that are close to the cut-off value, due to normal test variability.

About 90% of prostate cancers will over-express PCA3, but the PCA3 result cannot be used to diagnose or completely rule out prostate cancer. It just helps to guide decision-making on performing another biopsy. Prostate biopsy is still the gold standard for diagnosing prostate cancer.
Is there anything else I should know?

Many prostate cancers are slow-growing and not considered clinically significant. A man who has prostate cancer is more likely to live with the condition and die of something else. Prostate cancer may be managed through "watchful waiting" and treated if or when needed. Some prostate cancers, however, are aggressive and can grow and spread throughout the body. Distinguishing between the two can be challenging but is important. In recent years, there has been considerable concern about over-diagnosing and over-treating prostate cancers that are not clinically significant. In part, this is because the treatments carry the potential for significant complications that can impact a man's quality of life, including urinary incontinence and erectile dysfunction.

The medical community has become increasingly conservative about recommending PSA as a screening tool in asymptomatic men (See Screening Tests for Adults (30-49): Prostate cancer and Screening Tests for Adults (50 and Up): Prostate cancer for details on screening recommendations) and are eager to find additional tools that can aid in decision-making. PCA3 is one of these tools.

A wide range of other tests and biomarkers are being investigated.
Can I skip the digital rectal exam (DRE) and just collect a urine sample?

No, the DRE is a very necessary part of the sample collection. The procedure releases prostate cells and PCA3 into the urine, where it can be detected. This is why it is also important to collect the first amount of urine after the DRE – so the released PCA3 is present in the urine sample.
Can the test be performed in my healthcare practitioner's office?

The DRE will be performed in your healthcare practitioner's office and, most likely, so will the urine collection as it is the first urine collected after the DRE. However, the testing requires specialized equipment and your sample will be sent to a laboratory for testing. Not all labs perform this test, so your sample may be sent to a reference laboratory.
Will PCA3 testing detect all prostate cancers?

No, it is not over-expressed in every cancer, so about 10% of prostate cancers will have normal PCA3 results.

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View Sources

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Strong, A. and Deane, L. (2017). Contemporary Role of Biomarkers In the Evaluation, Stratification, And Treatment Determination in Men at Risk for and/or Diagnosed With Prostate Cancer. Urol Nurs. 2017;37(4):192-203. Urologic Nursing. Available online at https://www.medscape.com/viewarticle/892905. Accessed on 04/07/18.

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