Prospective diagnostic efficiency of biopsy washing DNA GSTP1 island hypermethylation for detection of adenocarcinoma of the prostate

BACKGROUND. The prospective diagnostic efficiency of quantitative glutathione S transferase (GSTP1) promoter hypermethylation analysis in biopsy washing samples has not been determined so far. METHODS. Biopsies were obtained prospectively from 86 patients suspicious for Prostate cancer (CaP). After isolation of DNA from biopsy washings and bisulfite conversion methylated and unmethylated GSTP1 sequences were specifically quantitated by real-time fluorescence PCR. Relative degrees of methylation were compared to results of histopathological examination. RESULTS. Increased relative methylation was found for the CaP group (mean 28.1%) compared to biopsies without histological evidence for malignancy (5.2%; P < 0.001). A sensitivity and specificity of 92% and 86% and positive and negative predictive values of 82% and 94% were obtained. Receiver operating characteristic (ROC) analysis demonstrated a value of 0.90 (95% CI 0.82-0.98) for the area under curve (AUC). CONCLUSIONS. Biopsy washing DNA GSTP1 hypermethylation analysis demonstrates a high diagnostic efficacy which is comparable to the retrospective analysis of biopsy tissue specimens. Moreover it is compatible with routine biopsy examination thus permitting further prospective evaluation in CaP diagnosis.