PSA is still the leading test for detecting prostate cancer—and it’s still controversial.
The PSA test, first approved by the FDA in 1986 as a way to monitor treatment of prostate cancer, is now widely used as a tool to screen for the presence of prostate cancer. Thousands of men, including public figures, have had their prostate cancer diagnosed with the help of this test (which measures prostate-specific antigen, a protein produced in the prostate and released into the blood). But the use of PSA testing has also been accompanied by controversy.
The Advantages of PSA Testing
Clinical studies have demonstrated the following benefits of PSA testing: 1) An elevated PSA is the single best predictor of the presence of prostate cancer; 2) PSA testing detects prostate cancer about 5 to 10 years earlier than digital rectal exams; 3) Most prostate cancers detected with PSA testing are curable; and 4) Serial PSA testing of a population leads to virtual elimination of advanced prostate cancer at the time of diagnosis.
The Drawbacks of PSA Testing
It is not clear whether using the PSA test to screen for prostate cancer actually reduces the risk of death from the disease. In addition, some men with an elevated PSA do not have prostate cancer, and some of the cancers detected by the PSA test are too small or too slow growing to be life-threatening. These men may undergo unnecessary biopsies (an expensive and unpleasant procedure) and other diagnostic tests and treatments and may experience undue anxiety.
Some experts have also called into question what constitutes a “normal” result on the PSA test—and argued that if the threshold were lower, more prostate cancers could be detected at an earlier stage, when they are more curable. A study in The New England Journal of Medicine appeared to support this view: It found that up to nearly 15% of 3,000 men with PSA scores at or below the established threshold (4 ng/mL) and a normal digital rectal exam had prostate cancer.
But to date, the available evidence suggests that, for most men age 50 and older, lowering the PSA threshold below normal will only lead to identifying more prostate cancers that would not cause a problem or wouldn’t even have been diagnosed during a man’s lifetime (unless revealed by a biopsy).
What Should You Do?
The American Cancer Society and American Urological Association recommend an annual PSA test beginning at age 50. Men at increased risk for prostate cancer—African-American men and men with a family history of the disease—should begin annual PSA screening at age 40 or 45.
A recent study by H. Ballentine Carter, M.D, Professor of Urology and Oncology at Johns Hopkins University School of Medicine, found that PSA testing for all men at age 40, age 45, and then every other year after age 50 may be a better strategy—it saved more lives and was less expensive. Another recent study suggests that men age 50 and older who have PSA levels below 2 ng/mL do not need annual testing.
Because of the controversies still surrounding the PSA test, it’s important that men discuss the benefits and drawbacks of PSA testing with their physicians before having their PSA levels measured.
When You Do Get Tested for Prostate Cancer
A number of factors may affect the results of a PSA test. For example, some studies show that ejaculation one or two days before a PSA test may increase PSA levels in the blood.
Consequently, men should abstain from sex for two days prior to a PSA test.
Digital rectal exams and biopsies of the prostate may also affect PSA levels, though the increase in PSA caused by a digital rectal exam is not thought to be significant enough to result in a false-positive test result. A biopsy, however, may elevate PSA levels for as long as four weeks.
In addition, other prostate problems, such as benign prostatic hyperplasia (BPH) or prostatitis, can inflate PSA levels, and BPH medications (such as finasteride and dutasteride) can lower PSA levels by about 50%. If any of these apply to you, be sure to discuss them with your doctor.
