Prostate cancer
test flawed, researchers say

A screening test for prostate cancer taken by millions of men every year is not terribly accurate, and not even the best result ensures that a man is cancer-free, experts said Tuesday. They found the standard prostate-specific antigen, or PSA test, produces many false positives and false negatives--meaning some men who think they do not have cancer actually do, while others may undergo uncomfortable biopsies only to learn there is no tumor after all.

"Patients have assumed, 'My PSA is below 4. It's normal. I have no risk,'" Ian Thompson of the University of Texas Health Science Center, San Antonio, who led the study, told a news conference. In fact, some men with PSA levels of 1 had prostate cancer, his study showed. Others with higher PSA levels did not have prostate cancer.

If all men got biopsies when PSA reached 1.1, more than 80% of all prostate cancers would be detected, Thompson said. But 61% of men who got biopsies would turn out not to have cancer. A cutoff of 2.6 would detect only 40.5% of cancer cases. This could explain why some men die of prostate cancer despite intensive screening programs, the researchers said.

"This is going to require a reeducation not just of patients but of physicians," Thompson said. "What should men do? Our take-home message--they should consider the risk factors."

"PSA, like blood pressure, like cholesterol, like many other tests, shouldn't be considered to be 'normal' or 'abnormal' but should be considered as showing a range of risk," Thompson said.

Men whose fathers or brothers had prostate cancer, African-American men, and others have a higher risk than the general population, for instance, he said. Prostate cancer affects more than 200,000 men a year in the United States and will kill 29,000 in 2005, according to the American Cancer Society. An American man has a 17% lifetime risk of prostate cancer, but only a 3% risk of dying from it. (Reuters)