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V. A. Multi-institutional Prospective study confirms the 4Kscore Test predicts Aggressive Prostate Cancer
Stephen M. Zappala, MD¹, Sanoj Punnen, MD², Stacy Loeb, MD³, Edward Uchio, MD⁴, Stephen Freedland, MD⁵, Thomas Polascik, MD⁶, Stephen Savage, MD⁷, Sharad Mathur, MD⁸, Michael Risk, MD⁹, Yan Dong, PhD¹⁰, Jonathan Silberstein, MD¹¹.
¹Andover Urology, Andover, MA, USA, ²Univ of Miami, Miami, FL, USA, ³New York University, New York, NY, USA, ⁴Univ California, Irvine, Irvine, CA, USA, ⁵Cedars-Sinai, Los Angeles, CA, USA, ⁶Duke Cancer Center, Durham, NC, USA, ⁷Univ of South Carolina, Columbia, SC, USA, ⁸Kansas City Veterans Center, Kansas City, MO, USA, ⁹Univ Minnesota, Minneapolis, MN, USA, ¹⁰OPKO Diagnostics, Woburn, MA, USA, ¹¹Tulane University, New Orleans, LA, USA.

Methods:Men were prospectively enrolled from eight VA locations. All were referred for prostate biopsy and underwent phlebotomy for 4Kscore prior to biopsy. Data was analyzed for discrimination, calibration, and clinical utility of the 4Kscore for predicting Gleason 7 or higher (G7+) CaP, and compared to a base model consisting of age, digital rectal exam findings, and PSA. Additionally, the 4Kscore test was compared amongst African-American (AA) and non-AA men.
Results: 403 men were enrolled and 366 had both 4Kscore and complete data available. Among these, 208 (56%) were AA, and 134 (36%) had G7+ CaP. The 4Kscore exhibited better discrimination (AUC: 0.81 vs. 0.74, p=0.011) and higher clinical utility on decision analysis than the base model. 4Kscore Calibration plots of for the entire cohort afforded predictions that closely matched the observed risk of G7+ CaP in the population. No difference in the discrimination of the 4Kscore test between AA and non-AA men (0.80 vs. 0.84; p=0.32) was seen. Because of the inherent higher risk for aggressive prostate cancer in African American men, a prospectively defined factor for modification of the 4Kscore for African American men was demonstrated to provide near perfect calibration for African American men while not impacting the calibration of non-African American men.
Conclusion: The 4Kscore test accurately predicts the likelihood of aggressive prostate cancer and outperforms standard clinical information for biopsy decision making in both AA and non-AA men.
Figure 1: Calibration Plot. Prediction of Gleason 7 or higher prostate cancer are plotted on the X-axis, while the actual observed rate of Gleason 7 or higher prostate cancer is plotted on the Y-axis. The solid diagonal line represents perfect calibration. The dotted line represents the calibration of the 4Kscore test, with predictions that closely approximate the observed risks.

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