Identification of occult prostate malignancy in a large patient cohort using a stereotactic transperineal prostate biopsy technique.

Abstract

9 Background: Continued rising PSA, despite prior transrectal prostate biopsy (TRPB), can cause significant anxiety for patients and physicians. This study investigates the detection rate of non-palpable, isoechoic occult malignancy using a stereotactic transperineal prostate biopsy (STPB) technique in patients with previous negative TRPB. Methods: 2,565 men with continued rising prostate specific antigen (PSA) with a minimum of 1 prior benign TRPB, underwent STPB at a single out-patient institution between 04/04 - 02/17 (See table). Specimens were obtained according to x, y, and z coordinates from 8 equal octants with pathology reported accordingly. A greater number of specimens were obtained from the apical half than the basilar half of the prostate; this was attributed to smaller glands in which the apical specimens sufficiently sampled the anterior curvature of the gland. Results: STPB yielded adenocarcinoma in 965/2,565 (37.6%) patients. The number of biopsy cores obtained per patient approximated the prostate gland volume in cm3. Statistical analysis demonstrated there was a significant difference in detection rates with the apex having a higher incidence of malignancy than the base of the prostate gland (p=.000). Furthermore, the anterior apex harbored significantly more adenocarcinoma when compared to the posterior apex (p=.026). Conclusions: STPB is efficacious for diagnosis of non-palpable, isoechoic occult prostate malignancy. Repeated sequential analysis of malignancy identification has consistently resulted in approximately 40% positive yield. Furthermore, a possible explanation for the significant finding in this study that occult malignancies occupy a higher percentage of apical biopsies using STPB may be related to difficulty and limitations of apical sampling using a standard transrectal biopsy approach. [Table: see text]