This is a brief overview of information related to FDA's approval to market this product. See the links below to the Summary of Safety and Effectiveness and product labeling for more complete information on this product, its indications for use, and the basis for FDA's approval.
Product Name: AxSYM Free PSA
Manufacturer: Abbott Laboratories
Address: 200 Abbott Park Road, Abbott Park, Illinois 60064
Approval Date: February 5, 2004
Approval Letter: http://www.accessdata.fda.gov/cdrh_docs/pdf/p980007a.pdf
What is it? The AxSYM Free Prostate Specific Antigen (free PSA) test is typically performed along with a total prostate specific antigen (total PSA) test and a digital rectal exam (DRE) to help distinguish between cancerous and non-cancerous (benign) prostate conditions.
The free PSA test measures the amount of PSA that is not attached to other substances (free-floating) in the blood. The total PSA test measures both the amount of PSA that is attached to proteins in the blood and PSA that is in the free-floating form. Once both tests are completed, a doctor compares the free PSA result to the total PSA result to determine the percent free PSA (% free PSA). The % free PSA, combined with the total PSA value and a DRE, helps determine whether a prostate biopsy is needed to rule out the risk (in percent) of cancer. The smaller the % free PSA, the more likely the patient is to have prostate cancer.
How does it work? A laboratory measures free PSA in a sample of the liquid part of a man’s blood (serum). During the AxSYM Free PSA test:
- free PSA from a serum sample is captured on microparticles coated with anti-PSA antibody,
- a second anti-PSA antibody attached to proteins binds to the PSA on the microparticles, and
- a chemical that reacts with proteins is added to the sample causing it to release fluorescent light.
- The amount of light released is proportional to the amount of free PSA in the sample.
- The less light released by the chemical, the smaller the amount of free PSA in the sample.
When is it used? A doctor uses a free PSA test along with a DRE and other tests to help diagnose prostate cancer and distinguish between cancerous conditions and benign conditions. A doctor will order this test when the patient:
- is a male who is 50 years or older,
- has a PSA level between 4 and 10 ng/mL, and
- has a prostate gland that appears of normal size and texture during a DRE.
What will it accomplish? When used with a total PSA test and DRE, the AxSYM Free PSA test can help determine the risk of prostate cancer. The use of % free PSA is expected to reduce the number of unnecessary biopsies, while identifying those men who have an increased probability of having prostate cancer.
When should it not be used? A doctor should not diagnose prostate cancer using only the results of the free PSA test. It should be combined with the total PSA test and a DRE. Diagnosis of cancer can confidently be made only by biopsy of the prostate gland. During a biopsy, a doctor:
- removes a small amount of prostate tissue and
- examines it under a microscope to determine if the growth is benign or cancerous.
The AxSYM Free PSA test should be delayed until at least two weeks after medical manipulation of the prostate, as it is known to release large amounts of PSA.
Additional information: Summary of Safety and Effectiveness and labeling will be available at: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cftopic/pma/pma.cfm?num=p980007