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New screening method helped identify cancer in men with negative biopsies
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Measuring the extent of change in PSA levels after treatment with two 5-alpha-reductase inhibitors may help diagnose aggressive prostate cancer in patients who have consistently abnormal PSA readings despite negative biopsies, according to recent results.
“Men with persistently increased serum PSA who have undergone multiple prostate biopsies with no detection of prostate cancer remain a challenging diagnostic dilemma for physicians,” the researchers wrote. “Despite the increase in prostate cancer detection rates resulting from enhanced prostate biopsy techniques, a significant number of patients with prostate cancer continue to have negative biopsies.”
Steven A. Kaplan, MD, and colleagues from Weill Cornell Medical College and New York-Presbyterian Hospital enrolled 276 men with a PSA greater than 4 ng/mL (n=208) or a PSA velocity change of 0.75 ng/mL (n=68) who had normal digital rectal examinations. All participants had undergone a minimum of two biopsies with negative results.
The patients received either 5 mg finasteride daily (n=154) or 5 mg dutasteride (Avodart, GlaxoSmithKline) daily (n=122).
In the first phase of the study, the researchers measured the PSA of 97 patients at 6 and 12 months, with repeat transrectal ultrasonography (TRUS) and biopsy performed at 1 year.
Overall, 1 year of drug therapy reduced PSA in all 97 men by a mean 2.4 ng/mL (–46.7%), and prostate volume decreased by a mean 7.1 mL (–17.9%), according to study results.
The researchers said PSA levels are sometimes increased by factors other than prostate cancer, such as the occurrence of benign prostatic hyperplasia.
Researchers detected prostate cancer in 27 of the 97 men evaluated in phase 1 of the study. The reduction in PSA from baseline was significantly greater (2.8 ng/mL vs. 2.1 ng/mL) in men found to have benign prostate disease than in those found to have cancer, according to researchers. The decrease in prostate volume also was greater among men with benign prostate disease than those with cancer (8.6 mL vs. 6.3 mL).
In the second phase of the study, 179 patients were assigned to the same drug therapy but underwent biopsy only if their PSA showed a change of more than 0.4 ng/mL. Forty-eight of the patients in phase 2 (26.8%) underwent repeat biopsies at a mean of 14.6 months. Of those men, 26 (54.1%) were determined to have prostate cancer.
Of the patients in which cancer was detected, 20 (76.9%) were found to have Gleason score 7 or greater disease, the researchers wrote.
The results demonstrated an ability to successfully identify prostate cancer based on drug therapy and evaluation of PSA trends, as only men with minimal changes were sent for biopsy, the researchers wrote.
“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,” Kaplan said in a press release. “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.”
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