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Prostate-specific antigen (PSA) tests are utilized by a wide variety of healthcare professionals – including family physicians, urologists and oncologists – to aid in the detection, monitoring, and management of prostate cancer. Different types of PSA tests can be used to guide decision-making at different stages of the disease. Physicians will often employ a test that measures total serum PSA for frontline risk assessment. A Free PSA (fPSA) test may be ordered when a patient exhibits a moderately elevated total PSA.
What is the prostate?
- It is a walnut-sized gland only found in men.
- It is located below the bladder and in front of the rectum.
- The urethra, which carries the urine, runs through the prostate.
- It also contains the cells that make semen.
What is prostate cancer?
- Prostate cancer is cancer that begins in the prostate gland.
- Most prostate cancers are small, slow growing tumors.
- Studies show that as many as 9 out of 10 men will have prostate cancer by age 80; however, the majority of these cancers will not be life threatening.
What is PSA?
- Prostate-specific antigen (PSA) is a protease produced primarily by the prostate gland.
- It is mostly found in semen but can also be found in bloodstream.
- PSA exists as Free PSA (fPSA) and PSA bound to protease inhibitors, which is known as Complexed PSA (cPSA).
What is a PSA test?
- A PSA test is the classic screening method that aids in the detection of prostate cancer.
- It is a simple blood test that measures the amount of PSA in the bloodstream.
- It is clinically accepted by the NACB and EGTM for both detection and monitoring.
- It is used in conjunction with a digital rectal examination (DRE).
Why is PSA measured?
- As PSA levels increase, the chance of a patient having prostate cancer increases.
- PSA testing in conjunction with a DRE is FDA-approved in men over 50 years. If a patient is considered high-risk due to family history or ethnicity, testing is recommended at age 45.
- PSA testing can be used in managing prostate cancer.
What do PSA values mean?
- Under 4.0 ng/mL is currently considered normal.
- Between 4.0 and 10 ng/mL is considered moderately elevated (the gray zone). A fPSA test can be used to help distinguish prostate cancer from benign prostastic hyperplasia when total PSA results are in the gray zone.
- Above 10 ng/mL is considered elevated.
What is the difference between Free PSA (fPSA) and Complexed PSA (cPSA)?
- FPSA is used in conjunction with total PSA to determine a percentage of fPSA value. The higher the percentage of fPSA, the more likely the patient has a non-cancerous disease such as benign prostatic hyperplasia or prostatitis.
- Measuring cPSA is more specific for prostate cancer than measuring total PSA alone 1-4.
- cPSA, like total PSA, is recommended as a frontline screening test.
How is prostate cancer diagnosed?
- A biopsy is taken to determine if cancer cells are present.
- The biopsy will be graded using the Gleason scoring system, which compares the patient’s biopsy to normal prostate cells.
- The most prevalent pattern and the second most prevalent pattern are graded on a scale from 1 to 5 and then added to create a total score between 2 and 10. Aggressiveness of cancer increases with the grade. In general, total scores between 2 and 4 are considered less aggressive; between 5 and 7 are considered moderately aggressive, and between 8 and 10 are considered the most aggressive.
- Imaging tests, such as bone scan, CT scan and MRI may also be employed to determine if cancer has spread.
What are other noncancerous diseases that affect prostate health?
- Benign prostatic hyperplasia (BPH) — enlargement of the prostate gland can cause varying degrees of urinary obstruction by constricting the urethra.
- Prostatitis — inflammation of the prostate gland can cause frequent or urgent need for urination accompanied by pain or burning.
- Elevated PSA values can be due to BPH or prostatitis.
- Both conditions are treatable and are not known to cause prostate cancer.
1. Parsons JK, Brawer MK, Cheli CD, Partin AW, Djavan R. Complexed prostate specific antigen (PSA) reduces unnecessary prostate biopsies in the 2.6-4.0 ng/mL range of total PSA. BJU Int. 2004 Jul;94(1):47-50.1
2. Lilja, et al. Significance of different molecular forms of serum PSA. Urol C Clin North Am 1993; 20:681:686.
3. Lilja H, Christtensson A, Matikainen M-T, et al. Prostate-specific antigen occurs predominantly in complex alpha-1-antichymotrypsin. Clin Chem 1991 ; 7 :1618-25.
4. Stenman UH, Leinonen J, Alfthan H, et al. A complex between prostate-specific antigen and alpha-1-antichymotrypsin is the major form of prostate-specific antigen in serum of patients with prostatic cancer: Assay of the complex improves clinical sensitivity for cancer. Cancer Res 1991; 51: 222-6.