DNA analysis by flow cytometry of paraffin embedded core biopsies of the prostate

The majority of literature concerning DNA analysis of prostate cancer involves testing formalin-fixed prostatectomy tissue, fresh or formalin-fixed transurethral resections of the prostate (TURP), or fresh core biopsies. We were interested if flow cytometry could analyze the DNA of formalin-fixed, paraffin-embedded, core biopsies separated into normal versus malignant segments. Of the 50 potentially available samples for analysis representing 11 controls of normal core tissue and 39 core biopsies from the 11 patients, one patient had no normal tissue, one core had no malignancy, and three cores had no tissue visibly remaining in the paraffin blocks for analysis. Therefore, of 45 actual samples available for processing, sometimes representing segments as small as 0.2 cm, separate segments containing malignant glands or normal glands were excised from the blocks, and processed separately by the Hedley technique. Forty-four of the 45 available samples produced interpretable DNA histograms as defined by discernible G0/G1 peaks, a calculable cell cycle analysis, and the qualitative appearance of a "smooth" histogram appearance, reflecting sufficient nuclei were analyzed. This is the first report to our knowledge where flow cytometry has successfully been used to analyze paraffin blocks of core biopsies which were, in addition, separated into malignant versus normal enriched segments.