Researchers Find PSA Prostate Test Unreliable

A study has found that pre-surgery prostate specific antigen (PSA) levels are not a useful predictor of any of the measured characteristics of prostate cancer. Moreover, surgical cure rates in men with PSA less than 4 ng/ml and men with levels as high as 10 ng/ml were found to be the same. Conducted by researchers at Stanford University Medical Center (Stanford, CA, USA), the study was published in the January 2002 issue of The Journal of Urology.

Since low levels of PSA have been thought to increase in men with early prostate cancer, men 50 and older whose levels exceed a certain cutoff may have a prostate biopsy. However, a biopsy cannot distinguish between a cancer that might be aggressive and a small one that will never harm a patient. As a result, prostate cancer is being over-diagnosed and over-treated, say the researchers. They found that low levels of PSA are not related to cancer but are caused by benign prostatic hyperplasia (BPH).

The researchers examined 875 prostates that had been surgically removed from cancer patients, measuring the volume of cancer, of Gleason grade four cancer, and other factors related to surgical success. They then determined whether these cancer-related factors were associated with PSA levels measured in the patients prior to surgery. The results showed that pre-surgery PSA was not a clinically reliable indicator of risk. A new marker is needed that can reflect the high-grade cancers, says the research team.

"Prostate cancer is incredibly ubiquitous,” said Thomas Stamey, M.D., professor of urology and primary author of the study. "It starts in men in their 30s and by age 90, almost all men will have some cancer in their prostate.” However, the risk of dying from prostate cancer is very low, he added.




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