PSA — Old controversies, new results

Nancy Ferrari

Senior editor, Harvard Health

The prostate-specific antigen (PSA) test to screen for prostate cancer is the most important issue in men’s health. It is also the most controversial. That’s because many experts believe prostate cancer is the exception to the rule that early detection of cancer saves lives. In fact, the PSA screening may actually do more harm than good.

Two much-anticipated studies, the results of which were released last month, were hopefully going to settle the debate over the value of the PSA. While they give us some much-needed answers, we are still a long way from settling the debate: Does PSA screening save lives by allowing doctors to treat aggressive cancers early, or does it harm men who would never die from the disease by subjecting them to the side effects of surgery, radiation, and/or hormone therapy?

The upside and downside of the PSA test

Most men in the United States over age 50 get the test, which was approved by the F.D.A. in 1994. Many men have the test repeatedly. That’s no surprise, since we value the early diagnosis of cancer along with the prompt and often aggressive treatments that follow.

The big picture

Prostate cancer is extremely common. Here’s a look at the numbers:

  • About 17% of American men will be diagnosed with prostate cancer during the course of their lifetimes.
  • The typical American man has just a 3% chance of dying from prostate cancer. In other words, only about one of every six clinically diagnosed prostate cancers will be fatal.
  • Many prostate cancers never even become large enough or troublesome enough to be diagnosed clinically.

The PSA can’t tell the difference between the slow growing, harmless prostate cancers and the less common, aggressive, potentially deadly tumors. In fact, the PSA can’t even diagnose cancer. Instead, depending on the score, it can lead to a prostate biopsy, which is the only way to detect the cancer. If doctors see cancer cells in the tissue sample, they try to estimate how aggressive the cancer is based on its appearance.

The upside of the PSA is that early diagnosis of aggressive prostate cancers can improve survival. But when screening finds cancers that would never cause symptoms or harm during the patient’s lifetime, it results in the major downside of PSA screening — over-diagnosis.

A cancer diagnosis usually leads to treatment, and all prostate cancer treatments carry a substantial risk of side effects. These may include sexual problems and urinary incontinence. As a result, diagnosing aggressive cancers can be lifesaving, but diagnosing harmless cancers does more damage than good.

The American study

The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial began in 1993. Over the next eight years, 76,693 men between the ages of 55 and 74 volunteered for the study, which took place at 10 U.S. medical centers. Scientists randomly assigned half of the men to annual PSA testing for six years, along with annual digital rectal exams (DRE) for four years. Men with PSA-test levels above 4.0 ng/ml or with abnormal DREs were advised to get further evaluation. This usually involved a prostate biopsy. Men in the comparison group continued to receive their usual medical care. Men in both groups who were diagnosed with prostate cancer were treated by their personal physicians. PLCO researchers found that both groups had similar treatments.

After seven years, the researchers found 22% more cases of prostate cancer in the men who had regular PSA screening. Even though PSA screening increased the diagnosis of prostate cancer, it did not improve survival. There were no real differences in the numbers of deaths in the two groups. About two-thirds of the men have completed another three years of follow-up in this ongoing study. The results at 10 years are similar to the previous findings.

The PLCO study will continue until all the volunteers have been evaluated for 13 years. Researchers are compiling information on treatment side effects and quality of life along with additional deaths.

The European study

Like the American study, the European Randomized Study of Screening for Prostate Cancer (ERSPC) began in the early 1990s. The study enrolled 162,243 men between the ages of 55 and 69. Scientists randomly assigned half of the men to receive PSA screening. The other half had their usual medical care. The study took place at medical centers in seven countries. PSA screening was performed an average of once every four years. Men with values of 3.0 ng/ml or above received prostate biopsies. Men who were diagnosed with prostate cancer were treated by their own physicians according to local guidelines.

After about 9 years of observation, 214 men in the PSA screening group and 326 men in the comparison group had died from prostate cancer. This means that screening reduced the relative risk of dying from prostate cancer by 20%. Here’s what this means to you in actual numbers. The risk of dying from prostate cancer is 3 in 100 (3%) for the typical American man. A 20% reduction means that with screening, the risk drops to 2.4 in 100 (2.4% ).

This very modest benefit came at a steep price: An additional 48 men who were not at risk of dying from prostate cancer had to be treated to prevent one death from the disease.

The ERSCP scientists will continue to monitor the deaths from prostate cancer, treatment side effects and quality of life for the men.

Should I have a PSA test?

Despite these major new studies, PSA testing remains a personal decision. But things have changed.

Before – There’s no evidence that PSA screening saves lives.

Now – There’s good evidence that screening does not save lives.

Before – If a man was undecided about having a PSA test, the best recommendation is to have the test.

Now – Unless a man has a particular reason to ask for the test, the best recommendation might be to skip the test.

The debate will continue, but the playing field has shifted.

One test, several roles

Doctors use blood PSA levels for several very different purposes.

  1. To diagnose prostate cancer in men who have symptoms or laboratory abnormalities that raise suspicion of the disease
  2. To evaluate the results of prostate cancer treatment
  3. To estimate the severity of benign prostatic hyperplasia (BPH), non-malignant enlargement of the gland

There is no controversy about these uses of the PSA test. The huge controversy is about the widespread use of the PSA to screen for prostate cancer in men who are free of signs and symptoms of the disease.

Originally published June 2009; last reviewed May 3, 2011.

Comments:

  1. Pake

    To the guy whose aggressive cancer was detected in time the test is a godsend.

    I am that guy.

  2. Randall

    I part of the 3% you right off. I was diagnosed with aggressive prostate cancer at 53 and I am alive due to a cheap fast PSA test easily performed as part of my routine physical. I tell every man I know to demand the test and demand it at a much earlier age.
    Physicians have no problems ordering un-necessary tests to cover their ass but want to dismiss a test proven it will save mine.

  3. joseph brown

    ERROR: -MY PSA TESTS–have been performed by: SIEMENS CENTAUR CHEMILUMINESCENT ASSAY:
    RECENTLY:
    the new methodoology is: ROCHE COBAS ELECTROCHEMILUMINESCENT IMUNASSAY.
    THIS PRESENTS A 20% POSITIVE BIAS IN CORRELATION TO THE SIEMENTS CENTAUR ASSAY.
    WHAT IS HAPPENING?? 20% POSITIVE BIAS IS BIG WHEN PSA # IS USED FOR TREATMENT OF P. CANCER…??

  4. joseph brown

    Since 2005 all my PSA tests (many @ MD Anderson; Houston) have been performed by .
    RECENTLY: the new methodology is: ROCHE COBAS ELECTROCHEMILUMINESCENT IMMUNASSAY….? Clinical Pathology Labs; Austin,Tx. state:
    “correlationstudies demonstrate appox.. 20% positive bias relative to prior Siemens Centuar Methodology.”

    WHAT IS HAPPENING?? AS THIS 20% BIAS PRESENTS MORE FEAR FACTOR IN USING AS THE MAIN GUIDANCE IN TREATMENT OF P.CANCER??

  5. Johnny

    I am very interested in learning more about the PSA testing. I go every 6 months for blood work (high blood pressure & diabetes) and I used to get the results of my PSA. It was always within normal range. Recently I have had issues with urination and have found what appears to be blood in my semen. I went back and looked at my blood work results for the past few years and realized that PSA testing wasn’t there. I called my doctor and he said that PSA testing had been removed from protocol and so he has not checked my PSA levels in about 4 years. Now I am concerned about possible prostate issues.

  6. Torie

    Whoever wrote this, you know how to make a good areltic.

Commenting has been closed for this post.