Using Genetic and Epigenetic Markers to Improve Differential Diagnosis of Prostate Cancer and Benign Prostatic...

Prostate cancer (PCa) is the most common malignancy in Mexican men. Serum prostate-specific antigen (PSA) is the usual noninvasive biomarker used for its detection. Its low specificity can increase the number of unnecessary prostate biopsies and the incidence of unpleasant complications for patients. The androgen-receptor gene (AR-CAG) repeat length and the percentage of promoter methylation (PPM) of genes glutathione-S-transferase P1 (GSTP1) and Ras association domain family 1 isoform A (RASSF1A) improve PCa detection. As an option for noninvasive assessment, we evaluated a combined analysis of all these biomarkers.

A total of 186 patients scheduled for biopsy were included in the present study. PSA and AR-CAG repeats were analyzed in blood samples. The PPM of GSTP1 and RASSF1A genes was estimated in prostate tissue and urinary sediment cells (USCs) and plasma DNA using quantitative methylation-specific polymerase chain reaction. The predictive values for PCa and benign prostatic hyperplasia (BPH), logistic regression analysis, receiver operating characteristic curve, and decision curve analysis were used to assess the differential diagnosis.

Statistically significant differences between PCa and BPH patients were observed for all biomarkers, with higher positive and negative predictive values when all biomarkers were included in the analysis, attaining USC values of 89.2% and 78.0%, respectively. The differential diagnosis accuracy of PSA (area under the curve, 0.59) increased to 0.70 and 0.68, respectively, when the combined analysis of PPM of RASSF1A_plasma or GSTP1A_USC and AR-CAG repeats was performed. Decision curve analysis showed the utility of the combined analysis to decrease the number of unnecessary biopsies.

The results showed that combined analysis of the proposed biomarkers in plasma and USCs significantly increased the confidence for the differential diagnosis for PCa and BPH. This noninvasive practice might help in the early detection of PCa and patient follow-up, avoiding to some extent unnecessary prostate biopsies.