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New Approach for Detecting Hard-to-Diagnose Prostate Cancer
The new study, announced on August 9 and published in the Journal of Urology, shows that the PSA level can be a more effective marker for prostate cancer when additional drug treatment is used than it can as a stand-alone test, which is how it is currently used by physicians.
"At a time when the value of PSA is being increasingly debated, we have shown that when used in a specific way, it can be of great value in identifying men with previously undetected prostate cancer," said lead investigator Dr. Steven A. Kaplan.
The researchers decided to see what would happen to PSA levels after treatment with finasteride and dutasteride, two 5-alpha-reductase inhibitors designed to reduce the size of enlarged prostates. The theory was that these drugs might improve the usefulness of PSA in diagnosing prostate cancer. If the PSA level remains persistently high even though the prostate has shrunk, or if the PSA rises after having reached its lowest level, it could indicate the presence of cancer. And when the gland is smaller, a biopsy can be more effective, according to the researchers.
The study was conducted in two phases. In the first phase, 97 patients were given 5.0 mg of finasteride or 0.5 mg of dutasteride daily and had their PSA levels measured at 6 and 12 months. A transrectal ultrasonography and a biopsy were performed at 1 year.
The researchers found that 1 year of drug therapy reduced PSA levels in all of the men by an average of 48%. The magnitude of the reduction was significantly greater in men with benign prostate disease and was significantly less in 28% of the patients whose prostate biopsies detected cancer.
In the second phase of the study, 179 patients received the same drug therapy but underwent a biopsy only if their PSA levels showed a change of 0.4 ng/dL. A total of 42 men (27%) received a biopsy, and 26 of those participants (54%) had cancer. Of the patients with cancer, 77% had high-grade tumors.
The researchers identified cancer cases in men who participated in the second phase of the study by sending those with minimal PSA changes for a biopsy. This meant that men who did not need a biopsy did not have one — unlike all of the men in the first phase of the study.
For more information, visit the Weill Cornell Medical Center Web site.