Widely Used Test Often Misses Prostate Cancer, Researchers Report

Many men who are told they do not have prostate cancer based on the results of a widely used blood test probably do have tumors, researchers reported yesterday.

The conclusion is based on a new study of nearly 3,000 men who were told by their doctors that they had nothing to worry about because their scores on the popular prostate-specific antigen (PSA) test fell within the "normal" range. The study found that 15 percent of them actually had tumors.

Although most of the cancers appeared to be so slow-growing that they were unlikely to ever require treatment, a small but significant portion of the malignancies were likely to become life-threatening, the study found.

"It's clear from our findings that there are many men with what is considered a normal PSA who are harboring cancer, and in some cases it may be aggressive prostate cancer," said Ian M. Thompson, chief of urology at the University of Texas Health Science Center at San Antonio, who led the study, published in today's issue of the New England Journal of Medicine.

The findings, the first to validate the suspicion that PSA testing is missing many cancers, rekindled a debate among physicians about how aggressively the tests should be used. Many experts argue that the PSA test is overused, frequently prompting men to undergo unnecessary biopsies and treatment for cancer that is growing so slowly it would never bother them. Others say that the opposite is true and that the guidelines for interpreting the results should be changed to catch more cancers.

"We're missing some dangerous cancers," said William J. Catalona, a professor of urology at Northwestern University who advocates lowering the cutoff point for ordering biopsies based on PSA results.

But others argued that there is still insufficient evidence that finding more cancers and treating them would save more lives.

"We are missing these prostate cancers, but we still don't have an answer to the fundamental question, which is: If we found them and treated them, would we make men live longer?" said Bruce "Ned" Calonge, chairman of the U.S. Preventive Services Task Force, which makes medical recommendations for the federal government. "That's that missing piece of evidence."

Prostate cancer strikes an estimated 220,900 U.S. men each year and kills about 28,900, making it the most common malignancy in males.

The prostate is a chestnut-size gland near the bladder that produces fluid for semen and surrounds the passageway that carries urine. The PSA test detects a protein produced by prostate cells called prostate-specific antigen, which can signal the presence of cancer.