An evaluation of frozen prostate sextant biopsies supplemented with basal cell specific cytokeratin immunohistochemistry

PURPOSE: Routine preparation of prostate needle biopsies in formalin eliminates most immunologic and biochemical assays and severely limits the amount of tissue available for research purposes. The present study evaluates the use of snap frozen needle biopsies in the diagnosis of prostate carcinoma. METHODS: 404 biopsies were obtained by transrectal ultrasonography guided needle biopsy. Core biopsies were snap frozen in isopentane cooled in freon. Serial sections of the frozen tissue were alternately stained with H&E and a slide with an antibody specific for basal cell cytokeratins. Age, incidence of high grade prostatic intra-epithelial neoplasia(HGPIN), prostate specific antigen(PSA), and results of digital rectal exam(DRE) were compared in those patients with and without diagnosis of prostate carcinoma. In patients with positive biopsies with subsequent radical prostatectomies, Gleason Sum score, tumor size and pathological stage were correlated with age, DRE, and PSA results. RESULTS: Out of the 404 patients, 158 (39.1%) were positive for carcinoma. No false positive biopsies were noted at time of radical prostatectomy. The table below shows the percentage of patients in the respective PSA ranges which were positive for malignancy with and without a positive DRE in patients with available data. PSA Range(ng/ml) DRE Positive DRE Negative 0-4 (n=17) 8/17= 47.1% No Biopsies Done 4-10 (n=170) 28/38= 73.7% 49/132=37.4% >10 (n=89) 22/23=93.6% 31/66=47.0% CONCLUSIONS: Our percent diagnosis of 39.1% positive for carcinoma compares favorably with other published reports of 44.8% and 31.0% using formalin fixed tissue. The absence of any false positive biopsies at evaluation of radical prostatectomy supports this technique which provides research material without compromising diagnosis. Future data analysis will link pre-biopsy PSA, DRE, age, incidence of HGPIN, in those patients positive for malignancy, and Gleason sum score, pathological stage, and tumor volume at radical prostatectomy.