The past 12 years have seen government guidance on the PSA screening test for prostate cancer bounce around like a rubber ball. Should men have an annual PSA test or not? Let’s start with the basics.
What Is The PSA test?
PSA stands for Prostate Specific Antigen. Antigens are tiny proteins on the surface of prostate cells. They act as a kind of ID tag, because they are specific to prostate cells. These proteins are “shed” into the bloodstream. When blood is drawn, a lab can determine the PSA concentration, reported as a numerical amount per volume. For example, if a PSA result is 2.5 ng/mL, it stands for 2.5 nanograms per milliliter.
Since all adult men have prostate glands, it is perfectly normal to have a small but detectable amount of PSA. The important thing to know is that having a PSA test every year is a way to monitor for any changes in the prostate. For example, as men age the prostate gland tends to enlarge, a noncancerous condition called BPH (benign prostatic hyperplasia). Since there are more prostate cells, from about age 50 onward it is not unusual for an annual PSA test to begin showing slight increases slowly over time. There is no cause for alarm or worry.
Other things can also cause a higher PSA result, because any activity in the gland causes more antigens to be released in the blood. This includes infection or inflammation, but it can also occur due to physical stimulation such as sexual activity, pressure from sitting on a bike seat, or a doctor performing a digital rectal exam (DRE or finger exam). Men are advised to avoid having sex or going on a long bike ride within a couple days before a blood draw. It’s also why the blood draw should be done before a DRE, which can cause a temporary spike in PSA that can be misinterpreted as prostate cancer.
Likewise, prostate cancer (PCa) itself causes PSA to rise. PCa cells are abnormal prostate cells, so they also have antigens. Since they behave more aggressively than normal cells, and multiply, they release more PSA in the bloodstream while also causing neighboring normal cells to shed more.
Here’s why the U.S. Preventive Services Task Force (USPSTF), a voluntary medical advisory board, has had mixed feelings about the PSA test. Roughly 1 out of 8 men will have PCa in their lifetime. However, early PCa—which is very treatable—has no symptoms. Before the PSA test was developed in the mid-1990s, most PCa patients were diagnosed with advanced PCa, and died from it. The PSA test changed all that! A high or rising PSA made early detection possible by sending up a red flag. Doctors then sent these patients for a needle biopsy to extract tissue samples from the prostate. These samples would be analyzed under a microscope by a specialist called a pathologist, who could give a definitive diagnosis that PCa was present. Suddenly, early detection of prostate cancer by the inexpensive PSA test began saving lives. Sounds good, right? So good, in fact, that by the year 2000, all men (starting at age 50 or younger, depending on risk factors) were urged to have annual PSA screening test.
The PSA Dilemma
But there’s a problem: a suspicious PSA result is not specific for cancer. A high number doesn’t necessarily mean PCa is present, but doctors are a cautious group. No responsible physician wants to take the chance of leaving cancer growing in man’s prostate gland—so the number of biopsies skyrocketed! Soon, a million prostate biopsies occurred each year in the U.S. Studies show rates of true positives (biopsy-proven PCa) up to roughly 50%, it means that about half of men who have a biopsy—which has risks of infection and discomfort—don’t have PCa.
Experts now increasingly believe that not all PCa is equally dangerous. Yet back then, men diagnosed with PCa were given two general choices: destroy the entire gland (surgery or radiation) or hold off on treatment while monitoring PCa growth using the PSA test. Patients who elected to have whole-gland treatment faced treatment risks of urinary, sexual and bowel side effects. When the USPSTF reviewed this situation, they concluded that the PSA test leads to three harms:
- Harm A: Way too many biopsies that were probably not needed, leading to
- Harm B: Way too many men receiving overly aggressive treatment that might not have been needed, leading to
- Harm C: Way too many men left with urinary incontinence, erectile dysfunction, and bowel problems—some of them for the rest of their lives.
The dilemma is, how to keep what’s good about the PSA yet get rid of the harms?
Resolving The Dilemma
The USPSTF could not see how to resolve the dilemma. Thus, their 2018 position is that men who are at low risk for PCa should talk with their doctors about the costs and benefits of a PSA test in their own situation. Sadly, since PSA became optional, the number of men being diagnosed at a later PCa stage has slowly been on the rise, due to the drop in the number of annual PSA tests.
Now there’s a solution. It began with a new specialized imaging technology called multiparametric MRI (mpMRI) which offers a 2-step way to resolve the dilemma.
Step one: Wait several weeks after an abnormal PSA test, then repeat the blood test (remember: no bike riding, sex or DRE prior to the blood draw). This rules out lab error, as well as unusual prostate stimulation before the previous test. Note that a repeat PSA does not rule out infection or inflammation, but there are other ways to diagnose such conditions.
Step two: If the repeat test is still high, have an mpMRI scan to determine if a biopsy is necessary. If suspicious are shows up on the scan, an MRI-guided targeted biopsy uses a minimal number of needles precisely directed into the area in question, thus providing the most accurate diagnosis possible with the least risk to the patient.
Statistics show the approximately 30% of biopsies prove unnecessary and can be avoided.
In my opinion as a physician who specializes in prostate cancer, it’s important to keep annual PSA screening as a standard of men’s health. It is a gateway into early detection, which leads to early diagnosis, which leads to appropriately matched treatment choices with fewer side effect risks. This preserves the life-saving benefits of PSA while protecting men from needless harms. And, for the record, taking this pathway also saves healthcare dollars in the long run by eliminating unnecessary biopsies, overly harsh treatments, and the cost of managing months and years of treatment side effects. To my mind, this is a win-win plan for all men.
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you have health concerns or questions of a personal medical nature.
