PD38-03 THE 4KSCORE IS ASSOCIATED WITH MORE ADVANCED DISEASE AT RADICAL PROSTATECTOMY; RESULTS FROM A MULTI-INSTITUTIONAL PROSPECTIVE TRIAL.

Abstract

INTRODUCTION AND OBJECTIVES: A recent prospective validation study confirmed the 4Kscore accurately predicted aggressive prostate cancer on biopsy of the prostate. Given the potential to miss aggressive cancer on biopsy, we investigated the association between the 4Kscore and pathologic grade and stage at radical prostatectomy, where the whole prostate gland is sampled. METHODS: Prospective enrollment of 1312 men who were referred for prostate biopsy for clinical suspicion of prostate cancer occurred at 26 sites throughout the United States from October 2013 to April 2014. We selected men who were found to have positive biopsies and elected to undergo radical prostatectomy. The 4Kscore is an algorithm that incorporates a panel of 4 kallikreins (total PSA, free PSA, intact PSA and human kallikrein‐2) in addition to age, digital rectal examination, and prior biopsy status. We assessed the concordance between the 4Kscore prior to biopsy and grade of prostate cancer at radical prostatectomy. Mean 4Kscores were compared for those with and without non organ‐confined tumors at surgery using the Wilcoxon rank‐sum. RESULTS: Among the 1312 men who enrolled in this validation study, 142 were found to have cancer and underwent radical prostatectomy. Among these men, 38 had non organ‐confined disease at radical prostatectomy. We saw a significant association between the 4Kscore and grade at surgery with higher scores relating to worse grade. For men with Gleason 6, 7, and 8 or higher cancers in the surgical specimen the median (IQR) 4Kscore was 8% (3,13), 24% (12,37), and 46% (23,68) (p<0.0001). The mean 4Kscore among men with non organ‐confined cancer was significantly higher then men with cancers confined to the prostate ([35% (IQR 18,58)] vs. [17% (IQR 8,35)], p=0.0003). CONCLUSIONS: In a subset of men who underwent radical prostatectomy, the 4Kscore was significantly associated with pathological grade and extra‐capsular pathology in the surgical specimen, with higher scores being linked to higher grade and more aggressive histology. The test can be beneficial to aid in treatment decision making for men who are contemplating observation of their cancer versus immediate treatment.