OBJECTIVES: To examine the morphologic alterations of finasteride therapy on prostate cancer compared with no treatment or treatment with a luteinizing hormone-releasing hormone (LHRH) agonist and the clinical outcomes of patients treated with finasteride.

METHODS: The data of 56 patients with prostate cancer who had taken finasteride for at least 6 months were reviewed. A central pathology review was performed in a blinded manner comparing these patients with 56 matched controls and 44 patients who received a 3-month course of LHRH agonist before radical prostatectomy. The histologic hormonal treatment effects included apoptosis, vacuolated cytoplasm, pyknotic nuclei, and small irregular glands. An overall consensus was scored using a three-tiered system: no apparent effect (score = 0), suspicious for hormonal effect (score = 1), and highly suggestive of hormonal treatment (score = 2). A Gleason score was assigned to all prostatectomy specimens.

RESULTS: The mean hormonal treatment score for the prostatectomy specimens was 0.4, 0.5, and 1.6 for the control, finasteride, and 3-month LHRH groups, respectively. Surprisingly, 20% of control patients had suspicious or highly suggestive hormonal effects and 26% of the finasteride-treated patients did so. For the LHRH-treated group, only 23% did not demonstrate classic features of hormonal treatment. Similar clinical outcomes were observed between the finasteride and control groups.

CONCLUSIONS: No consistent hormonal therapy effects with finasteride treatment were observed compared with LHRH agonists. The hormonal effect was observed in the control group. Therefore, although other aspects of the Prostate Cancer Prevention Trial design might account for the greater percentage of Gleason grade tumors in the study arm, morphologic changes due to long-term finasteride treatment were not a likely cause.