Background TMPRSS2:ERG (T2:ERG) and prostate cancer antigen 3 (PCA3) are the most advanced urine-based prostate cancer (PCa) early detection biomarkers.
Objective Validate logistic regression models, termed Mi-Prostate Score (MiPS), that incorporate serum prostate-specific antigen (PSA; or the multivariate Prostate Cancer Prevention Trial risk calculator version 1.0 [PCPTrc]) and urine T2:ERG and PCA3 scores for predicting PCa and high-grade PCa on biopsy.
Design, setting, and participants
T2:ERG and PCA3 scores were generated using clinical-grade transcription-mediated amplification assays. Pretrained MiPS models were applied to a validation cohort of whole urine samples prospectively collected after digital rectal examination from 1244 men presenting for biopsy.
Outcome measurements and statistical analysis
Area under the curve (AUC) was used to compare the performance of serum PSA (or the PCPTrc) alone and MiPS models. Decision curve analysis (DCA) was used to assess clinical benefit.
Results and limitations
Among informative validation cohort samples (n = 1225 [98%], 80% from patients presenting for initial biopsy), models incorporating T2:ERG had significantly greater AUC than PSA (or PCPTrc) for predicting PCa (PSA: 0.693 vs 0.585; PCPTrc: 0.718 vs 0.639; both p < 0.001) or high-grade (Gleason score >6) PCa on biopsy (PSA: 0.729 vs 0.651, p < 0.001; PCPTrc: 0.754 vs 0.707, p = 0.006). MiPS models incorporating T2:ERG score had significantly greater AUC (all p < 0.001) than models incorporating only PCA3 plus PSA (or PCPTrc or high-grade cancer PCPTrc [PCPThg]). DCA demonstrated net benefit of the MiPS_PCPTrc (or MiPS_PCPThg) model compared with the PCPTrc (or PCPThg) across relevant threshold probabilities.
Incorporating urine T2:ERG and PCA3 scores improves the performance of serum PSA (or PCPTrc) for predicting PCa and high-grade PCa on biopsy.
Incorporation of two prostate cancer (PCa)-specific biomarkers (TMPRSS2:ERG and PCA3) measured in the urine improved on serum prostate-specific antigen (or a multivariate risk calculator) for predicting the presence of PCa and high-grade PCa on biopsy. A combined test, Mi-Prostate Score, uses models validated in this study and is clinically available to provide individualized risk estimates.
Approximately 1 million men undergo prostate biopsy each year in the United States, most for elevated serum prostate-specific antigen (PSA or KLK3). Serum PSA’s lack of prostate cancer (PCa) specificity, the unclear benefits of PSA screening for reducing PCa deaths, and the harms of overdiagnosing indolent disease have called PSA screening into question [1–3]. Although aggressive PCaspecific biomarkers may eventually replace serum PSA, at present, methods to individualize management of elevated PSA are needed. Such approaches include multivariate risk models, such as the Prostate Cancer Prevention Trial risk calculator (PCPTrc), which includes serum PSA and clinical factors [4–6]. Likewise, multiple PSA derivatives and other related kallikreins have been advanced as early detection biomarkers, including free PSA and proPSA (both of which are incorporated, with total PSA, in the Prostate Health Index [PHI]), with free PSA and PHI approved by the US Food and Drug Administration (FDA) for PCa risk estimation in men with serum PSA of 4–10 ng/ml [7–9]. Similarly, a panel of free and total PSA, single-chain intact PSA, and a related kallikrein (KLK2) outperforms serum PSA alone for predicting PCa on biopsy, and a test incorporating these kallikreins along with clinical parameters (4Kscore) is available [7,9].
In summary, we reported validated individualized risk models (MiPS) incorporating serum PSA (or the PCPTrc) and urine T2:ERG and PCA3 scores for predicting PCa and highgrade PCa risk on needle biopsy. By AUC, assessment of unnecessary biopsies avoided, and DCA, MiPS models significantly outperformed serum PSA (or PCPTrc)-based strategies, supporting the use of the MiPS test as a decisionmaking aide for men (and their physicians) concerned about serum PSA test results, particularly in the initial biopsy setting. The MiPS test, which uses these validated models to report quantitative risk assessments for PCa and high-grade PCa on biopsy, is clinically available through a College of American Pathology/Clinical Laboratory Improvement Amendments–certified laboratory. Additional studies will be needed to compare MiPS performance with other early detection–based strategies and to determine costs and benefits of various early detection approaches.