Andrew Siegel MD 4/27/19
When I use the acronym PSA, I do not refer to “Public Service Announcement,” nor “Pacific Southwest Airlines,” nor “Polar Surface Area.” In the context of this entry, PSA is Prostate Specific Antigen, an important blood test that helps screen for prostate cancer and monitor prostate cancer in those diagnosed with the disease.
What is PSA?
PSA is a chemical produced by the prostate gland, that functions to liquefy semen following ejaculation, aiding the transit of sperm to the egg. A small amount of PSA filters from the prostate into the blood circulation and can be measured by a simple blood test. In general, the larger the prostate size, the higher the PSA level, since larger prostates produce more PSA. As a man ages, his PSA rises based upon the typical enlarging prostate that occurs with growing older.
How is PSA used to screen for prostate cancer?
Using PSA testing, about 90% of men have a normal PSA. Of the 10% of men with an elevated PSA, 30% or so will have prostate cancer. In a recent study of 350,000 men with an average age of 55, median PSA was 1.0. Those with a PSA < 1.5 had a 0.5% risk of developing prostate cancer, those between 1.5-4.0 had about an 8% risk, and those > 4.0 had greater than a 10% risk.
Although it is an imperfect screening test, PSA remains the best tool currently available for detecting prostate cancer. It should not be thought of as a stand-alone test, but rather as part of a comprehensive approach to early prostate cancer detection. Baseline PSA testing for men in their 40s is useful for predicting the future potential for prostate cancer. The most informative use of PSA screening is when it is obtained serially, with comparison on a year-to-year basis providing much more meaningful information than a single, out-of-context PSA.
I have practiced urology in both the pre-PSA and the post-PSA era. In my early career (pre-PSA era), it was not uncommon to be called to the emergency room to consult on men who could not urinate (a condition known as urinary retention), who on digital rectal exam were found to have rock-hard prostate glands and imaging studies that showed diffuse spread of prostate cancer to their bones—metastatic prostate cancer with a grim prognosis. Fortunately, in the current era, that scenario occurs extremely infrequently because of PSA screening. These days, most men who present with metastatic disease are those who have not had PSA screening as part of their annual physical exams.
Is there any truth that the PSA test is worthless?
A major backlash against screening occurred a few years ago with the United States Preventive Services Task Force (USPSTF) grade “D” recommendation against PSA screening and their call for total abandonment of the test. This organization counseled against the use of PSA testing in healthy men, postulating that the test does not save lives and leads to more tests and treatments that needlessly cause pain, incontinence and erectile dysfunction. Of note, there was not a single urologist on the committee. The same organization had previously advised that women in their 40s not undergo routine mammography, setting off another blaze of controversy. Uncertainty in the lay press prompted both patients and physicians to question PSA testing and recommendations for prostate biopsy.
Is there really any harm in screening? Although there are potential side effects from prostate biopsy (although they are few and far between) and there certainly are potential side effects with treatment, there are no side effects from drawing a small amount of blood. The bottom line is that when interpreted appropriately, the PSA test provides valuable information in the diagnosis, pre-treatment staging, risk assessment and monitoring of prostate cancer patients. Marginalizing this important test does a great disservice to patients who may benefit from early prostate cancer detection. I give the USPSTF an “F” for their ill-advised recommendation, the aftermath of which is, sadly, a spike of men with higher PSA levels and more aggressive and advanced prostate cancer.
Since the early 1990s, prostate cancer mortality has declined, but the aftermath of the USPSTF recommendation was a spike in prostate cancer death rates
The USPSTF gets the Horse’s Ass award for disservice to the well- being of mankind
Why bother screening for prostate cancer?
Excluding skin cancer, prostate cancer is the most common cancer in men (1 in 9 lifetime risk), accounting for one-quarter of newly diagnosed cancers in males. Prostate cancer causes absolutely no symptoms in its earliest stages and the diagnosis is made by prostate biopsy done on the basis of abnormalities in PSA levels and/or digital rectal examination. An elevated or accelerated PSA that leads to prostate biopsy and a cancer diagnosis most often detects prostate cancer in its earliest and most curable state. Early and timely intervention for those men with aggressive cancer results in high cure rates and avoids the potential for cancer progression and consequences that include painful cancer spread and death.
The upside of screening is the detection of potentially aggressive prostate cancers that can be treated and cured. The downside is the over-detection of unaggressive prostate cancers that may never prove to be problematic, but may result in unnecessary treatment with adverse consequences. The downside of not screening is the under-detection of aggressive prostate cancers, with adverse consequences from necessary treatment not being given.
Why is PSA elevated in the presence of prostate cancer?
Prostate cancer cells do not make more PSA than normal prostate cells. The elevated PSA occurs because of a disruption of the cellular structure of the prostate cells. The loss of this structural barrier allows accelerated seepage of PSA from the prostate into the blood circulation.
Does an elevated PSA always mean one has prostate cancer?
There is no letter C (for cancer) in PSA. Not all PSA elevations imply the presence of prostate cancer. PSA is prostate organ-specific but not prostate cancer-specific. Other processes aside from cancer can cause enhanced seepage of PSA from disrupted prostate cells. These include prostatitis (inflammation of the prostate), benign prostatic hyperplasia (BPH, an enlargement of the prostate gland), prostate manipulation (e.g., a vigorous prostate examination, prostate biopsy, prolonged bike ride, ejaculation, etc.).
Why is PSA an imperfect screening test?
PSA screening is imperfect because of false negatives (presence of prostate cancer in men with low PSA) and false positives (absence of prostate cancer in men with high PSA). Despite its limitations, PSA testing has substantially reduced both the incidence of metastatic disease and the death rate from prostate cancer.
Who should be screened for prostate cancer?
Men age 40 and older who have a life expectancy of 10 years or greater are excellent candidates for PSA screening. Most urologists do not believe in screening or treating men who have a life expectancy of less than 10 years. This is because prostate cancer rarely causes death in the first decade after diagnosis and other competing medical issues often will do so before the prostate cancer has a chance to. Prostate cancer is generally a slow-growing process and early detection and treatment is directed at extending life well beyond the decade following diagnosis.
The age at which to stop screening needs to be individualized, since “functional” age trumps “chronological” age and there are men 75 years old and older who are in phenomenal shape, have a greater than 10-year life expectancy and should be offered screening. This population of older men may certainly benefit from the early diagnosis of aggressive prostate cancer that has the potential to destroy quantity and quality of life. However, if a man is elderly and has medical issues and a life expectancy of less than 10 years, there is little sense in screening. Another important factor is individual preference since the decision to screen should be a collaborative decision between patient and physician.
Bottom Line: PSA screening detects prostate cancer in its earliest and most curable stages, before it has a chance to spread and potentially become incurable. PSA screening has unequivocally reduced metastases and prostate cancer death and it is recommended that it be obtained annually starting at age 40 in men who have a greater than a 10-year life expectancy. PSA testing in men who have been diagnosed with prostate cancer provides valuable information about pre-treatment staging, risk assessment and monitoring after treatment. Although PSA has many shortcomings, when used intelligently and appropriately, it will continue to save lives.
Wishing you the best of health,
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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery. He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States.
The content of this entry is excerpted from his new book, PROSTATE CANCER 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families
Video trailer for Prostate Cancer 20/20
Preview of Prostate Cancer 20/20
Andrew Siegel MD Amazon author page
Prostate Cancer 20/20 on Apple iBooks
Dr. Siegel’s other books:
PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food
MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health
THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health
Our Greatest Wealth Is Health 