INTRODUCTION AND OBJECTIVE:
Active surveillance (AS) is a management option for men with low-risk prostate cancer (GG1, PSA<10 ng/mL); however sampling error, genomic variability, and multi-focality complicate AS shared decision-making. The ExoDx Prostate (EPI; Exosome Dx, US) pre-biopsy urine liquid biomarker test is non-invasive and validated for risk assessment of high-grade prostate cancer (HGPCa). Herein, we explore the potential of the EPI test to predict surgical pathology upgrading risk on RP) and as an aid in categorizing patients who may be less suitable for AS.
Men with no history of PCa, >50yrs, PSA 2-10 ng/mL, were scheduled for diagnostic prostate biopsy (Bx). First-catch, pre-Bx urine was collected (sites in US, Europe) and EPI tests performed. We focus on men with biopsy Gleason Grade Group 1 (GG1) pathology who underwent RP instead of AS. The pre-biopsy EPI scores in the GG1-group were compared to a multiparametric linear regression model using clinical covariates PSA, age, ethnicity and family history for correlation with pathologic upgrading on RP.
Samples were collected from N=1563 patients (2014 to 2020). 295 men subsequently proceeded to RP and a further subset (N=106, 36%) had GG1 on Bx. Between the Bx-GG1 (N=106) and the Bx>GG1 (N=189) groups, we found no significant differences in age (60 [57-65] vs 64 [59 - 68] years; p=0.61), PSA value (median PSA 5.32 [4.3 - 6.47] vs 5.48 [4.3 - 7.0] ng/mL; p=0.66), African ancestry (2.8% vs 7.4%; p=0.89) or family history of PCa (32% vs 25%; p=0.33). In the Bx-GG1 group, 45% (48) were confirmed GG1 on RP and 55% (58) were upgraded – 41% (43) GG2, 11% (12) GG3, 1% (1) GG4, and 2% (2) GG5. The multiparametric model showed no significant differences between the groups (p>0.1). EPI scores for patients who remained GG1 vs those upgraded to GG2 showed no significant difference (p=0.45), whereas EPI scores were significantly higher (p<0.01) for patients upgraded to ≥GG3 on RP.
The current study provides initial evidence that the EPI test, validated for pre-Bx HGPCa risk stratification, may have value for assessing RP pathologic upgrading in GG1 cancer. The EPI urine liquid biomarker test assay might more appropriately assess tumor heterogeneity and thus have a role in AS decision-making in newly diagnosed GG1 prostate cancer.
Source of Funding:
Study was funded by Exosome Diagnostics, Waltham, MA, USA