Prostate Specific Antigen (cont.)
Kevin C. Zorn, MD, FRCSC, FACS
Dr. Kevin Zorn is a dual-board-certified (US and Canada), minimally-invasive uro-oncology, fellowship trained urologist at the University of Chicago. His main focus of clinical and scientific interest is in the surgical treatment of renal and prostate cancer. He is also an expert in performing surgery with the DaVinci Surgical Robotic System to manage localized prostate cancer and small renal masses. Dr. Zorn studied medicine and urology at McGill University in MontrĂ©al.
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
In this Article
- Prostate specific antigen (PSA) facts
- What is prostate specific antigen?
- How is PSA measured?
- What causes PSA elevation in the blood?
- What are normal results for the PSA test?
- What are age-specific reference ranges for serum PSA?
- How is PSA used for early detection prostate cancer?
- What is the free PSA test?
- What is free/total PSA ratio?
- What is PSA velocity and PSA doubling time?
- How is PSA testing used for pretreatment staging of prostate cancer?
- How is PSA testing used in the management of prostate cancer posttreatment?
- What are the limitations of the PSA test?
- What is digital rectal examination (DRE)?
- What is the PSA screening controversy?
- How should the PSA test be used for the early detection of prostate cancer?
- What is PCA3?
How should the PSA test be used for the early detection of prostate cancer?
Ultimately, the decision to use PSA for the early detection of prostate cancer should be individualized. Men should be informed of the known risks and the potential benefits of early screening. Not all men are appropriate candidates for screening efforts. For instance, screening in men with less than a 10-year life expectancy, either due to age or other illness, is discouraged as there will be most likely no benefit for them.
If prostate cancer is detected on prostate biopsy, all treatment options should be discussed. The benefits and risks of the many treatment options should be reviewed and discussed with men found to have prostate cancer. The AUA recommends that this discussion include active surveillance as a consideration, since some prostate cancers detected with screening in certain men may not need immediate treatment. The goal of active surveillance is to allow men to maintain their quality of life when the disease is slow-growing or inactive, but still allow them to be cured of prostate cancer when the disease appears to become more aggressive or is growing. Other novel biomarkers, such as PCA3 (see below), may assist the clinician in these decisions.
What is PCA3?
A newly discovered biomarker is known as PCA3 (prostate cancer antigen 3). PCA3 may help to discriminate between cancer-related versus nonspecific PSA elevations. PCA3 was initially identified comparing prostate cancer tissue with nonmalignant normal prostatic tissue. PCA3 is a type of genetic material known as noncoding RNA that is found at high levels in prostate cancerous tissue. But unlike PSA, it is only present at a low level in benign prostatic tissue. Hence PCA3 can be considered a prostate cancer specific marker.
While PSA is detected in the blood, PCA3 is measured in the urine obtained after prostatic massage. The main advantages of PCA3 over PSA testing are its higher sensitivity and specificity. In particular, PCA3 may be useful for identifying prostate cancer in men who initially had negative biopsies despite an elevated PSA. This is why the use of a PCA3 test may help reduce the number of potentially unnecessary biopsies generated by nonspecific positive PSA screening tests. Despite its promising role in helping the doctor counsel or confirm biopsy indications, use of the PCA3 test for now is still considered experimental.
American Urological Association. "Prostate-Specific Antigen Best Practice Statement: 2009 Update." American Urological Association Education and Research, Inc. Nov. 2009. <http://www.auanet.org/content/guidelines-and-quality-care/clinical-guidelines/main-reports/psa09.pdf>.
Andriole, G. L., et al. "Prostate cancer screening in the randomized Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial: mortality results after 13 years of follow-up." Journal of the National Cancer Institute 104.2 (2012): 125-132.
Gomella, L. G., et al. "Screening for prostate cancer: the current evidence and guidelines controversy." Canadian Journal of Urology 18.5 (2011): 5875-5883.
Richardson, T. D. and J. E. Oesterling. "Age-specific reference ranges for serum prostate-specific antigen." Urologic Clinics of North America 24.2 (1997): 339-351.
Schröder, F. H., et al. "Screening and prostate-cancer mortality in a randomized European study." New England Journal of Medicine 360.13 (2009): 1320-1328.
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