May 21, 2002 -- When the PSA blood test hit doctors' offices years ago, we thought it would change the world of prostate cancer testing. But in the minds of many experts, it only created confusion. And researchers at a meeting of cancer specialists say many men are having the test too often.
The PSA (prostate specific antigen) blood test is widely used to check men for signs of prostate cancer. But there is a problem with this strategy. While cancer causes PSA levels to increase, PSA also goes up as the prostate enlarges with age -- a very common problem in elderly men. And even when the PSA increase is due to cancer, that cancer may not be aggressive and may never be life threatening.
A normal PSA level is less than 4 ng/mL, but levels above 4 are considered suspicious and require additional testing, such as CT scan and biopsy. These additional tests are expensive and may still not tell the whole picture. In some cases, this may lead to exploratory surgery -- only to find out that the man never had aggressive prostate cancer to begin with.
So, while many doctors recommend annual PSA testing, others are reluctant to do so given this confusion.
E. David Crawford, MD, associate director at the University of Colorado Health Sciences Center, Denver, says results of a new study can help sort out this dilemma.
In a study of more than 27,800 men who underwent PSA testing annually for five years, Crawford discovered a pattern in the tests that suggests only about half of men over age 55 need annual PSA testing. He reported the findings at the American Society of Clinical Oncology meeting.
"We found that the vast majority of men whose initial PSA levels are very low do not need to worry that they will skyrocket within one year," says Crawford. The men in the study were all aged 55 to 74.
When a man has a PSA of less than 1 ng/mL, it is so unlikely that his PSA will increase quickly that he can wait five years for another test, says Crawford. If the level is between 1 and 2 ng/mL, the man is safe having his PSA checked every two years.
Men with PSA levels above 2 should probably stick to a yearly test schedule, says Crawford.
"If all men followed this practice about $500 million to $1 billion could be saved annually," he says.
"These findings get away from a larger question of whether PSA screening tests should be done at all. Screening can be harmful," says Steven Woolf, MD, professor of family practice, preventive medicine and community health, at Virginia Commonwealth University, Fairfax.
He says that screening often causes as many problems as it solves. Unnecessary screening often leads to unnecessary biopsies and prostate surgery for cancers that likely would have caused no disease in the man's lifetime, Woolf says.
While Woolf applauded Crawford's study, he says it is not enough. He says doctors are waiting for well-designed studies to determine how PSA screening can best benefit men.
"We are not good at telling which of these early detected prostate cancers will go on to become invasive cancers," he says. -->