Clinical Sensitivity and Specificity of the PROSTest in an American Cohort.

Introduction: Prostate cancer (PCa) is the most commonly diagnosed cancer in men in the United States, following skin cancer, with an incidence rate of 112.7 per 100,000 men per year. The need for a reliable, non-invasive diagnostic tool for early PCa detection (screening, biochemical residual disease) remains unmet due to the limitations of PSA testing, which often leads to overdiagnosis and overtreatment. The PROSTest is a novel, blood-based qPCR assay that assesses gene expression to diagnose PCa and predict patient outcomes to different treatments. This study aimed to validate the sensitivity and specificity of the PROSTest in a diverse cohort of US-based PCa patients compared to healthy controls.

Materials and methods: This prospective study included 143 PCa patients and 92 healthy controls. Blood samples were collected, and the PROSTest was conducted following RNA isolation and cDNA production, using a predefined 27-gene algorithm to provide a binary output. The assay's sensitivity and specificity were evaluated using receiver operating characteristic (ROC) analysis, with a 50% score cut-off distinguishing PCa from non-PCa patients. Analytical reproducibility was assessed with intra- and inter-assay comparisons of Ct values and PROSTest scores.

Results: The PROSTest demonstrated a sensitivity of 94% (95% CI 89-98%) and a specificity of 88% (95% CI 80-94%) in distinguishing PCa patients from controls, with an area under the ROC curve (AUROC) of 0.97. The false positive rate among controls was 12%. Intra- and inter-assay reproducibility was confirmed with no significant differences in Ct values or PROSTest scores between operators or assays. PROSTest scores were significantly higher in PCa patients compared to controls and in those undergoing treatment versus untreated patients.

Conclusion: This validation study confirms the high sensitivity and specificity of the PROSTest in detecting PCa in a diverse USA cohort. The assay's robustness and reproducibility support its potential as a reliable diagnostic tool for PCa detection and monitoring. Further studies are warranted to evaluate its utility across broader populations and treatment settings.