PSA Worthless for Prostate Cancer Screening?
'PSA Era Over,' Test's Pioneer Now Says
PSA Still Useful
Even Stamey agrees that PSA tests are useful for some purposes, such as monitoring the success of prostate cancer surgery.
Carter argues that PSA tests aren't used properly.
"We could improve the test by focusing our efforts on younger men, where the discovery of cancer is more relevant and PSA is a much better test," he says. "But we are screening the wrong age group. We are treating the wrong age group."
Carter also argues that single PSA measurements give much less information than multiple tests. He'd like to see the test used differently.
"I think the way to use this test correctly, which gets rid of a lot of the noise in the test -- the false positives -- is to start PSA screening at age 40. Then you'd test again at age 45, and every year after 50, and put together a long PSA history. Then you could use that PSA trajectory to tell us who is gong to get into trouble."
By the time a man is 70, Carter says, PSA testing no longer yields valuable information.
Parnes says there are three things men should know about PSA screening:
- It's not yet known whether prostate cancer screening saves lives. A major government study is looking at the question, but the results won't be known for years.
- Screening poses risks as well as benefits. Yes, early detection can save the life of a person with an aggressive cancer. But biopsies cost money, and they are no picnic. And prostate cancer treatments run high risks of leaving men with urinary incontinence and erectile dysfunction.
- In Parnes' opinion, PSA tests are hard to evaluate. "There is no magic PSA threshold below which a man can be assured there is no risk, or above which a biopsy should be automatically performed," he says.
Stamey, Parnes, and Carter all advise men to discuss their risk of prostate cancer -- and the risks of prostate cancer screening -- with their doctors.