Cancer Research Lab

Men whose prostate specific antigen (PSA) concentration remains elevated often undergo multiple prostate biopsies without finding any evidence of prostate cancer. Now, the results of a pilot study suggest that 6 months’ treatment with finasteride can help differentiate patients with prostate cancer because the drug reduces PSA density far more among those free of cancer.

Dr. Steven I. Cohen and his associates note that approximately 70% of prostate biopsies are unnecessary, but there is no consensus on how to manage men who have had multiple biopsies with negative results, but continue to have elevated PSA levels.

In their report in the December issue of Urology, the physicians at Brown University in Providence, Rhode Island, explain that finasteride, used to treat benign prostatic hypertrophy, inhibits 5-alpha-reductase, so that testosterone cannot be converted to dihydrotestosterone, thereby decreasing prostate volume, PSA, and PSA density.

Dr. Cohen’s group initiated a prospective, pilot study that included 23 men, median age 67, with PSA levels > 4.0 ng/mL, who had already undergone at least one negative prostate biopsy. The subjects received finasteride 5 mg/day for 6 months and underwent 12-core prostate biopsies at baseline and after 6 months’ treatment.

The prostate volume was calculated using the formula for an ellipse (width x length x height x 0.52). The PSA level divided by the prostate volume determined PSA density.

At the 6- month check-up, six patients were diagnosed with adenocarcinoma of the prostate. In this group, median PSA, prostate volume, and PSA density at baseline declined from 9.6 to 5.8 ng/dL, 29.20 to 25.85 cc, and from 0.300 to 0.285, respectively.

In the 17 patients free of cancer at 6 months, corresponding values for median PSA levels, prostate volumes, and PSA density declined from 7.6 to 4.1 ng/dL, 53.55 to 52.35 cc, and from 0.142 to 0.080.

The authors note that patients with prostate cancer had a 5% decrease in PSA density, while those without cancer had a 44% decrease. However, the test missed one patient with cancer, whose PSA density fell more than 50%.

Dr. Cohen and his associates acknowledge that their results were not “perfect” or statistically significant. Still, they say, the results suggest that changes in PSA density may be useful in differentiating patients with benign prostatic hypertrophy from those who are developing prostate cancer, and that a larger prospective study is warranted.