New Use for PSA in Prostate Cancer

Researchers have discovered a new use for prostate-specific antigen (PSA) testing that indicates outcome following treatment. Their findings were reported in the September 20, 2005, issue of the Journal of Clinical Oncology.

Among men whose disease relapsed after radiation or surgery and who subsequently received hormonal treatments, the researchers found that those whose PSA did not drop to an undetectable level--less than 0.2 ng/ml--had a much poorer outcome than those whose levels did drop. They call this new indicator "PSA nadir.”

The study involved 747 men, aged 45-88, who were followed for up to 9.5 years. Of the 28 observed prostate cancer deaths in this group, 21 (75%) occurred in men whose PSA nadir was more than 0.2 ng/ml and who had a PSA doubling time of less than three months. The latter is a known indicator of aggressive disease. Patients whose PSA nadir was more than 0.2 ng/ml experienced a 20-fold increase in death from the disease.

"Many men with relapsed prostate cancer will still have a median survival of more than a decade after being given hormonal treatment,” observed lead author Alexandria Stewart, M.D., formerly of Brigham and Women's Hospital (BWH) and Dana-Faber, both affiliated with Harvard University (Boston, MA, USA; www.harvard.edu). "Some men, however, will have shorter survival if their PSA does not drop below 0.2 ng/ml. This indicates that PSA nadir could be used as an additional diagnostic tool to help determine the success of treatment. If PSA nadir is detected earlier, it could prompt physicians to more aggressively treat the disease.”






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