GLEASON HISTOLOGIC GRADING IN PROSTATIC-CARCINOMA - CORRELATION OF 18-GAUGE CORE BIOPSY WITH PROSTATECTOMY

Histologic grading of adenocarcinoma of the prostate gland is a reliab le predictor of extension and metastasis. Studies involving correlatio n of grade between biopsy and prostatectomy specimens have traditional ly involved biopsies using a large-bore (14-gauge) cutting needle. How ever, common practice has shifted to the use of biopsy cores with a sm aller caliber (18 gauge). This study was undertaken to determine the d egree of correlation of tumor grade between 18-gauge core biopsy sampl es and excised glands. Sixty-seven patients with stage A or B adenocar cinoma of the prostate gland who had previously undergone 18-gauge cor e biopsy, who underwent radical prostatectomies, were studied. The Gle ason score was determined by refereed consensus among three pathologis ts. There was exact agreement between biopsy and excision in 39 cases (58%),whereas 24 cases (36%) differed by one digit. Three cases (4.5%) were undergraded, and one case (1.5%) was overgraded by two or more p oints. Only six tumors (8.9%) would have been incorrectly specified by the degree of differentiation. Discrepancies in grade of two points o r more were not more frequent in cases with a small tumor volume (less than or equal to 10%) in the biopsy specimens. We concluded that with careful histologic evaluation, the grade of tumor identified in these smaller biopsy cores correlates well with that seen at prostatectomy.