(RxWiki News) Men can have elevated PSA (prostate-specific antigen) levels, and later undergo a biopsy only to find out that they do not have prostate cancer. That's a problem with PSA tests - they don't distinguish between benign (non-cancerous) disease and prostate cancer.
Drugs designed to shrink enlarged prostates in men with abnormal PSA levels but normal biopsies can help to diagnose prostate cancer.
"Discuss prostate cancer screening with your doctor."
Steven A. Kaplan, MD, professor of urology at Weill Cornell Medical College and director of the Iris Cantor Men's Health Center at NewYork-Presbyterian/Weill Cornell, led the study.
"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 Dr. Kaplan.
"We have shown that using PSA with these drugs can help us differentiate prostate cancer from benign prostate disease in patients who are difficult to diagnose," says Dr. Kaplan.
These drugs are known as 5 alpha-reductase inhibitors and both are approved by the U.S. Food and Drug Administration (FDA) to treat enlarged prostates, as well as male baldness. They work by blocking male hormones.
E. David Crawford, MD, professor of surgery, urology, and radiation oncology, and head of the Section of Urologic Oncology at the University of Colorado Health Sciences Center (UCHSC) in Denver, told dailyRx, "Men on these agents should have an approximate 50 percent drop in their PSA after 6-9 months of therapy, and if they don't, this could signal prostate cancer."
The two-phase study involved 276 men who had PSA levels of greater than 4 ng/ml. They had each had digital rectal exams and at least two negative biopsies that revealed nothing.
For the first phase, 97 men received 5 milligrams of finasteride or 0.5 milligrams of dutasteride daily. They had PSA tests after 6 and 12 months. An ultrasound and biopsy were performed at 12 months.
PSA levels dropped an average of 48 percent in all men during the year. The decrease was much greater in men with benign prostate disease - and much less with men who had a positive biopsy.
In the second phase of the study, 179 men took the same drug therapy, but had biopsies only if their PSA changed by 0.4 ng/dl. A total of 47 men had a biopsy and 54 percent of these men had prostate cancer. This means, of course, that nearly half of the men who had the therapy and biopsies did not have cancer.
Dr. Crawford, who says he has seen this dilemma in his own practice, said, "The PSA drop on 5 alpha reductase agents becomes a diagnostic test for the absence of cancer as a cause of PSA elevation."
"In my experience, even in men who cut their PSA in half, any change from these new baseline, is worrisome and may indicate the need for more thorough biopsies which we label-mapping biopsies," said Dr. Crawford, who was not involved in this study.
"There are some other tools that can help us discern who has cancer including a urine test called PCA3, which was recently FDA approved to use in men who have had negative biopsies. Additionally, a prostate MRI can be helpful," Dr. Crawford said.
This study was published in the September issue of The Journal of Urology.
Funding information was not available. Dr. Kaplan disclosed financial relationships with pharmaceutical manufacturers Pfizer, Astellas and Watson. Other authors have relationships with Imalux anb Boston Scientific.