Pathological changes of high‐grade prostatic intraepithelial neoplasia and prostate cancer after monotherapy with bicalutamide 150 mg

OBJECTIVES To evaluate the morphological changes induced by a 3‐month course of neoadjuvant bicalutamide 150 mg/day before radical prostatectomy (RP) on prostatic adenocarcinoma and high‐grade prostatic intraepithelial neoplasia (HGPIN). PATIENTS AND METHODS In all, 90 patients with cT1–T2 prostate cancer and HGPIN on prostatic biopsy were randomized to receive bicalutamide (150 mg/day for 3 months) before RP, or to have immediate surgery. Surgical specimens were assessed for the histopathological features of cancer, HGPIN and benign epithelium in a blinded manner. The volumes of prostate cancer and HGPIN were evaluated using a stereological (i.e. grid) method. RESULTS Compared with the bicalutamide‐treated group, the ratio of stroma to epithelium, evaluated by visual microscopic assessment in the normal epithelium of the three prostate zones, was significantly lower in the control group, at 2.27 (sd 1.13), than in the treated group, at 1.87 (sd 0.72) (P = 0.048). The mean (sd) tumour volume was significantly lower in the bicalutamide‐treated than in the control group, at 0.914 (0.13) vs 1.47 (0.24) mL (P = 0.044). Similarly, the mean (sd) volume of HGPIN was significantly lower in the bicalutamide‐treated than in the control group, at 0.34 (0.06) vs 0.62 (0.07) mL (P = 0.003). At RP, specimen Gleason scores in the bicalutamide‐treated group were similar to those in the control group, and were no different from the biopsy Gleason scores. CONCLUSIONS Involution and epithelial shrinkage of prostate cancer and HGPIN were evident after neoadjuvant treatment with bicalutamide 150 mg. There was no evidence of the emergence of higher‐grade cancer after treatment.