Clinical significance of urine-based automated detection of GSTP1 methylation for the diagnosis of suspected prostate cancer patients

Abstract

Background: Glutathione S-transferase Pi-1 (GSTP1) methylation is detectable in prostate cancer (PCa) tissues, blood, and urine post-prostate massage, with elevated levels in urine samples. But its role in urine samples for PCa diagnosis is still unclear. This study aimed to investigate the clinical significance of urine-based automated detection of GSTP1 methylation technology in the diagnosis of clinical suspected PCa patients.

Methods: A retrospective study was performed on 120 patients who underwent prostate biopsy at The University of Hong Kong-Shenzhen Hospital from September 2022 to June 2024. All patients underwent digital rectal examination (DRE) prior to biopsy, with post-DRE urine samples used for GSTP1 methylation testing. Using biopsy pathology as the gold standard, we compared the sensitivity, specificity, and accuracy of urinary GSTP1 methylation with prostate-specific antigen (PSA) for diagnosing PCa. Additionally, we developed a diagnostic prediction model integrating urinary GSTP1 methylation and PSA to assess the combined method's value in enhancing diagnostic efficacy.

Results: The sensitivity and specificity of urinary GSTP1 methylation for PCa diagnosis were 81.4% and 83.6%, respectively, with positive predictive value (PPV) of 82.8% and accuracy of 82.5%. In contrast, PSA had sensitivity and specificity of 67.8% and 54.1%, respectively, with PPV of 58.8% and accuracy of 60.8%. Urinary GSTP1 methylation showed no significant difference in sensitivity compared to PSA (P=0.16) but significantly higher specificity (P=0.001). In the PSA gray zone (4.0-10.0 ng/mL), GSTP1 methylation had sensitivity and specificity of 87.5% and 86.2%, respectively, achieving accuracy of 86.7%, demonstrating good diagnostic efficacy. The area under the curve (AUC) for the combined urinary GSTP1 methylation and PSA method was 0.89 [95% confidence interval (CI): 0.84-0.95], P<0.001, significantly superior to PSA alone, notably improving diagnostic efficacy.

Conclusions: Automated detection of urinary GSTP1 methylation significantly enhanced PCa diagnostic value, outperforming PSA in sensitivity, specificity, and accuracy. Combining urinary GSTP1 methylation with PSA notably improved accuracy, especially in the PSA gray zone (4.0-10.0 ng/mL), demonstrating excellent efficacy. This non-invasive, easily performed method showed high diagnostic efficacy, indicating strong clinical potential.

Keywords: Prostate cancer (PCa); diagnosis; glutathione S-transferase Pi-1 (GSTP1); prostate-specific antigen (PSA); urine-based automated detection.

Figure 1

Flowchart of included patients. BPH, benign prostatic hyperplasia; GSTP1, glutathione S-transferase Pi-1; PCa, prostate cancer.

Figure 2

The diagnostic efficacy of urinary GSTP1 methylation and PSA. (A) The diagnostic power of GSTP1 methylation. (B) The diagnostic power of PSA. (C) The diagnostic power of the combination of GSTP1 methylation and PSA. (D) The diagnostic power of GSTP1 methylation in PSA gray zone. AUC, area under the curve; CI, confidence interval; GSTP1, glutathione S-transferase Pi-1; PSA, prostate-specific antigen.