Prostate biopsy in response to a change in nadir prostate specific antigen of 0.4 ng/ml after treatment with 5α-reductase inhibitors markedly enhances the detection rate of prostate cancer.
We examined the effect of 5α-reductase inhibitor therapy on prostate cancer detection in men with persistently increased or fluctuating prostate specific antigen and prior negative prostate cancer biopsy. A total of 276 men with prostate specific antigen greater than 4 ng/ml (208) or a prostate specific antigen velocity change of 0.75 ng/ml (68) and a normal digital rectal examination who had previously undergone biopsy a minimum of 2 times with prostate cancer not detected were given 5 mg finasteride (154) or dutasteride (122) daily. In phase 1, 97 patients had prostate specific antigen measured at 6 and 12 months with repeat transrectal ultrasonography and biopsy (12 cores) performed at 1 year. In phase 2, 179 patients underwent biopsy triggered by a change in nadir prostate specific antigen of more than 0.4 ng/ml. In phase 1 at 1 year prostate specific antigen had decreased by 2.4 ng/ml (-46.7%), and prostate volume had decreased 7.1 ml (-17.9%). Prostate cancer was detected in 27 of 97 (27.8%) patients and the mean minimum prostate specific antigen velocity from a nadir of 0.4 ng/ml was 0.6 ng/ml. In phase 2, 48 of 179 (26.8%) men underwent repeat biopsy at a mean of 14.6 months. Of these 48 men 26 (54.1%) were found to have prostate cancer. Of the 26 men in whom prostate cancer was detected 20 (76.9%) were found to have Gleason score 7 or greater disease. The magnitude of change in serum prostate specific antigen after 5α-reductase inhibitor therapy may be useful in diagnosing prostate cancer in patients with persistently increased or fluctuating prostate specific antigen and prior negative prostate biopsy.