Limitations of transition zone needle biopsy findings in the prediction of transition zone cancer and tissue composition of benign nodular hyperplasia.

OBJECTIVES: The transition zone of the prostate is the origin of 30% of all prostate cancers and of almost all benign prostatic hyperplasia (BPH). We compared histologic findings in transition-zone biopsies to tissue composition of the transition zone from radical prostatectomy specimens from the same patients to determine the efficacy of needle biopsies to evaluate either cancer or BPH.
METHODS: A quantitative evaluation of the transition zone for both cancer and BPH in 21 retrospective and 11 prospective radical prostatectomy specimens was made. All retrospective cases had transition-zone biopsies prior to radical prostatectomy; all prospective specimen transition zones were biopsied after surgical removal with an ink-filled needle to trace the needle tracks after specimen processing. For all 32 specimens, total prostate weight, width of transition zone, transition-zone tissue composition, and epithelial/stromal (E/S) ratio of nodular and internodular BPH tissue were noted; the corresponding biopsies were evaluated for the amount of cancer and the composition of nodular and internodular tissue.
RESULTS: Eight carcinomas larger than 5.0 cc were detected at biopsy, whereas 5 cancers smaller than 2.0 cc were undetected. Biopsies did not reliably predict BPH tissue composition or epithelial density of prostatectomy specimens; both were markedly underestimated. Dyed needle tracts showed selective sampling of internodular tissue versus nodules by biopsy as an explanation for low correlations.
CONCLUSIONS: Transition-zone needle biopsies efficiently detect cancers larger than 5.0 cc and miss cancers smaller than 2.0 cc. Biopsies do not reliably predict BPH tissue composition because of selective sampling of the internodular tissue.