Is the PSA Test Still Worthwhile?

What to Know About the Prostate Cancer Screening Tool

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When the prostate-specific antigen (PSA) blood test was approved in 1994 as a screening tool for the early detection of prostate cancer, it was hailed as a medical breakthrough that would save countless lives.

Before then, the lack of a systematic detection method had meant that prostate cancer often wasn’t diagnosed until it had spread to other parts of the body, greatly increasing the likelihood it would be fatal.

In every year since the PSA test’s introduction, the rate of prostate cancer deaths has declined, and cases of advanced prostate cancer at the time of diagnosis have fallen by 75 percent.

Confusion and Controversy

Sounds like a success story, right?

But barely a generation later, the PSA test is the subject of much confusion and controversy. It has earned a failing grade from an expert medical review panel that recommended against its routine use, and it seems to have fallen out of favor among many physicians and patients.

That has happened in large part because PSA finds too many low-grade cancers that are not destined to be harmful, needlessly exposing many men to the worry, cost, and potential complications of cancer treatment.

How did we get here, and what role, if any, does PSA have in prostate cancer screening? Is the test still worthwhile?

Proper Use

The short answer to that last question is yes.

The PSA test can provide valuable information when it’s used properly.

While I and other urologists share the concerns about overtreating non-lethal prostate cancers, many of us think the criticisms of the PSA test have been overstated.

When used in a rational way, the test still has value. To understand what I mean, let’s back up a bit and examine what led to our current situation.

Indolent Cancers

First, it’s important to know that not all prostate cancers are the same.

Many tumors grow very slowly or not at all, and cause little or no symptoms. These kinds of tumors are called indolent.

Since prostate cancer mainly occurs in older men—the average age at diagnosis is 66—and since treatment with surgery and radiation can have unwanted side effects, such as impotence or incontinence, the logical thing to do in these slow-growing cases is just to keep an eye on things. The medical term for this is active surveillance, which means periodic checkups and re-evaluation of the cancer’s aggressiveness.

Nearly 100 percent of patients whose cancer has not spread outside of their prostate live at least five years after diagnosis. Put another way, the time it would take for an indolent prostate tumor to progress and cause harm in these patients, if it ever does, is often longer than their remaining lifespan.

Aggressive Cancers

Other prostate cancers, however, are aggressive, fast-growing, and potentially fatal.

They require timely treatment. The earlier they’re detected, the better the odds of success.

Patients whose cancer is still relatively contained to their prostate and nearby tissue when diagnosed are almost certain to be alive in five years. But those whose prostate cancer has spread to distant lymph nodes, bones, or other organs have a dismal 29 percent five-year survival rate.

So you can see why early detection is important. But it’s only half the battle. Being able to predict the course of a patient’s prostate cancer—knowing whether it’s the slow-growing, no-action-required kind, the aggressive, fast-spreading kind, or something in-between—also is crucial.

Improving the Finger Test

For most of the 20th century, the only prostate cancer screening tool doctors had was their lubricated, rubber-gloved index finger—the dreaded digital rectal exam, or DRE.

Probing the organ for signs of enlargement or lumps gave a hint of whether a tumor was present. But it wasn’t definitive, it certainly wasn’t comfortable, and it couldn’t provide any information about the cancer’s likely course. A surgical tissue biopsy and other follow-up tests were used for that determination.

As you can imagine, by the time a prostate tumor was large enough to be felt, it probably was fairly advanced, which meant it likely wasn’t curable. The DRE was hardly an ideal early-detection method.    

Then along came the PSA test. It detects the amount of a protein called the prostate-specific antigen that’s produced by the cells of the prostate gland and circulates in the bloodstream.

The PSA level often is elevated in men with prostate cancer. The combination of the DRE and PSA test dramatically improved our ability to catch prostate tumors early.

PSA’s Drawbacks Include Overdiagnosis

But the PSA test has a number of downsides, too.

First, other things besides prostate cancer can cause PSA levels to rise—non-cancerous conditions such as prostate inflammation or the enlargement that happens with aging, for example. Second, there’s no clear-cut “normal” PSA level. Many men with a high PSA result don’t actually have prostate cancer, while some with low levels do. Third, the test’s “false-positive” rates are high, causing needless worry in patients who don’t actually have cancer. And finally, the PSA test can’t distinguish between slow-growing cancers that don’t need treatment and aggressive ones that do. 

The widespread adoption of the PSA test beginning in the 1990s meant that lots more prostate cancers were detected at an early stage, before any symptoms—a good thing for those needing immediate treatment, but not so good for those who didn’t.

Prostate cancer survival rates increased, but so did the number of men with indolent tumors who unnecessarily underwent biopsies, had their prostate surgically removed, endured radiation therapy, and experienced the unfortunate side effects of those procedures.

Two large studies estimated the rate of prostate cancer “overdiagnosis” (the detection of a non-life-threatening tumor) due to PSA test results at between 17 and 50 percent.

And researchers found no clear evidence that regular PSA screening was directly responsible for a significant drop in cancer deaths. (The decline in prostate cancer death rates I mentioned in the second paragraph of this article could be due to a number of other factors, including improved treatments.)  

Groups Disagree About Testing

So what doctors and patients were left to wrestle with was a test that seemed like a mixed bag: It detected lots of early-stage cancers, whether they needed treatment or not, and it didn’t seem to be making much of a dent by itself in the number of prostate cancer deaths.

By 2008, the U.S. Preventive Services Task Force, an influential panel of experts in primary care and preventive medicine (but not urology or cancer), recommended that men 75 and older not undergo PSA screening. In 2012, the panel broadened its advisory against PSA testing to include men of all ages, saying the test’s harm outweighed its benefits.   

Several other medical groups disagreed, arguing that younger patients with potentially curable prostate cancers, and those at increased risk (such as men of African descent and those with a family history of prostate cancer) would still gain from regular PSA testing. They warned that a decline in screening might cause a return to the days when prostate cancer wasn’t detected until its advanced, incurable stage.

Without agreed-upon guidelines, doctors and patients were caught in the middle. Doctors often left the testing decision to their patients. PSA screening rates did fall, and so did the diagnoses of early-stage (and presumably inconsequential) prostate cancers.

Worryingly, though, a recent study reported that the number of newly diagnosed cases of advanced prostate cancer has sharply risen since 2007. While there’s been some criticism of the study’s methods, it’s not a stretch to think that less prostate cancer screening means more cases of important and treatable cancers won’t be caught until they’ve spread.

A Rational Approach to the PSA Test

So in this confusing environment, what’s a patient supposed to do? Ideally, someone would invent a smarter screening test—one that not only reliably identifies early-stage prostate cancer but can accurately predict its course, clarifying whether and how to treat.

Fortunately, there are improved screening tests in the pipeline, as well as other developments that should help improve diagnostic accuracy.

Meanwhile, here’s the approach to PSA testing I recommend and that I use with my patients:

  • Get an initial “benchmark” PSA at age 50. Your doctor can order the test and discuss the results with you. If the test result, combined with your medical history and other clinical information indicates a low risk of developing prostate cancer, follow-up PSA testing should be repeated every five years.
  • If your initial PSA test and medical information at age 50 show an elevated risk of prostate cancer but you have no symptoms, you should have a screening every other year using one of the smarter blood tests I mentioned earlier (the 4Kscore or Prostate Health Index tests), and possibly an MRI scan of the prostate. Talk with your doctor about these options. Based on the follow-up results from these tests, you and your doctor can decide together what additional steps, if any, are needed. 
  • If by the age of 60 your PSA level is below 2 nanograms per milliliter, your chance of developing aggressive prostate cancer in the remainder of life is very small—1 or 2 percent. At that point, it’s safe to repeat the PSA test much less often than every five years, or stop testing altogether.

With this common-sense approach, we can still catch high-grade cancers that need treatment while also reducing the likelihood of diagnosing low-grade tumors that aren’t harmful but would cause needless worry and treatment.

Dr. Klein is Chairman of Cleveland Clinic’s Glickman Urological & Kidney Institute, the nation’s No. 2 urology program as ranked by U.S. News & World Report. 

Sources:

Barocas DA, Mallin K, Graves AJ, et al. Effect of the USPSTF Grade D Recommendation against Screening for Prostate Cancer on Incident Prostate Cancer Diagnoses in the United States. J Urol. 2015 Dec;194(6):1587-93.

Barry MJ, Nelson JB. Opposing Views: Patients Present with More Advanced Prostate Cancer since the USPSTF Screening Recommendations. J Urol. 2015 Dec;194(6):1534-6.

Catalona WJ, D'Amico AV, Fitzgibbons WF, et al. What the U.S. Preventive Services Task Force missed in its prostate cancer screening recommendation. Ann Intern Med. 2012 Jul 17;157(2):137-8.

Moyer VA, LeFevre ML, Siu AL, et al. Screening for prostate cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2012 Jul 17;157(2):120-34.

 Surveillance, Epidemiology, and End Results (SEER) Program Stat Fact Sheets: Prostate Cancer. National Cancer Institute. Accessed at http://seer.cancer.gov/statfacts/html/prost.html

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