Diagnostic frozen prostate sextant biopsies: An approach for preserving protein and RNA for additional studies

BACKGROUND. Primary prostate cancer represents 29% of newly diagnosed visce ral cancers in men. Despite this common occurrence, relatively little is kn own about the pathogenesis of this malignancy. High-grade prostatic intraep ithelial neoplasia (HGPIN) is generally accepted as a precursor to invasive prostate carcinoma. There is a lack of adequate animal models, and the ava ilable cell culture lines are limited. Tissue from prostate needle core bio psies that have been frozen can provide adequate material for both diagnosi s and research. METHODS. Transrectal sextant needle biopsies were snap-frozen, serially sec tioned and alternately stained with hematoxylin-eosin or reacted with a bas al cell-specific antibody. Two pathologists examined all of the sections, w hich were scored for the presence or absence of carcinoma and HGPIN. Portio ns of the remaining tissue were used for studies of protein expression and gene expression RESULTS. The incidence of carcinoma was 39%, comparable to the mean percent positive cases reported using conventional fixation and paraffin embedding . The incidence of HGPIN was 33%, higher than previously reported. CONCLUSIONS. Prostate carcinoma can be accurately diagnosed using frozen ma terial. The observed high frequency of HGPIN is attributed to the instabili ty of nuclear structure in the frozen material of the atypical nuclei, resu lting in inflated grading of PIN lesions. Sufficient material remained in t he frozen blocks for additional studies of protein and gene expression (C) 2000 Wiley-Liss, Inc.