Presentation Authors: Amit Bhattu*, Miami, FL, Yan Dong, Woburn, MA, Alexander Kong, Miami, FL, Stephen Zappala, Andover, MA, Dipen Parekh, Sanoj Punnen, Miami, FL
Introduction: Two independent prospective trials have validated the 4Kscore test for predicting clinically significant cancer. However, they assessed the 4kscore test as a continuous score. We wanted to illustrate the use of a 7.5% cut off for deciding on the need for prostate biopsy using combined data from both trials.
Methods: This study pooled data from two prospective multi-institutional trials. One was conducted in 26 primarily community-based U.S. urology practices and the other was conducted at 8 U.S. Veterans Affairs Medical Centers. Men in both the trials were 40-80 years old and referred for biopsy of the prostate. A minimum 10-core biopsy was required, and phlebotomy was done before for 4Kscore ascertainment. The primary outcome was presence of Gleasons score â‰¥ 7 on biopsy. We performed exploratory analysis to evaluate the number of biopsies avoided and cancers detected using a 4Kscore cut off of 7.5% using the entire cohort, and various subgroups.
Results: This analysis included 1378 patients who had a 4Kscore and biopsy, of which 1012 patients were from the original validation study and 366 were from Veterans Affairs study. The analysis showed that 32.2% of biopsies would have been avoided by applying a 4Kscore threshold of 7.5% for prostate biopsy. The sensitivity for detecting Gleason â‰¥ 7 cancer using a 7.5% cut-off was 94%, while the negative predictive value for ruling it out was 95%. There were no Gleason 8 or higher prostate cancers missed when using this cut off for proceeding with a biopsy. Among patients with a 4Kscore less than 7.5%, prostate biopsy findings were benign in 76.1% patients, revealed a Gleason 6 in 19.1%, Gleason 3+4=7 in 3.4% patients, and Gleason 4+3=7 in 1.4% patients (Figure 1). Subgroup analyses in patients with a PSA between 3-10ng/ml, and between African American and non-African American men revealed no difference in the risk of significant cancer in those with a 4Kscore below 7.5%.
Conclusions: The 4Kscore is noninvasive biomarker that helps to facilitate biopsy decision-making. We found that using a 7.5% cut-off allowed a significant biopsy reduction with high sensitivity for detection, and a high negative predictive value for ruling out aggressive prostate cancer.
Source of Funding: OPKO diagnostics