Clinical validation of the iXip index in avoiding unnecessary prostate biopsy: Results from a prospective multicenter study involving 426 patients

To assess the diagnostic accuracy of iXip, a novel biomarker for prostate cancer detection at initial biopsy based on an algorithm including patient age, prostate volume, PSA and PSA-IgM levels,. This was a prospective multicenter study involving 426 consecutive men undergoing initial prostate biopsy with at least 12 cores in a real-life clinical setting. Diagnostic accuracy of iXip for prostate cancer detection was calculated with AUC and compared to that of prostate volume, PSA and PSA-IgM levels. The correlation of iXip with tumor aggressiveness, defined as any cancer with Gleason score ≥7, was evaluated by Spearman ρ coefficient analysis. Prostate cancer was diagnosed in 193/426 patients (45%), of which 65 (35%) had Gleason score ≥7. iXip values were significantly higher in patients with cancer than in those without cancer (median value 55% vs. 39%, p<0.001). iXip was the most accurate predictor of cancer (AUC=0.711), followed by prostate volume (AUC=0.660) and PSA level (AUC=0.543). By setting iXip cut-off at 20%, no patients with iXip values below the cut-off were diagnosed with cancer, resulting in a 5.6% (24/426) reduction of unnecessary prostate biopsies. A significant correlation between iXip values and Gleason score was observed (ρ=0.347; p<0.001). Our prospective multicenter study suggests that the novel biomarker iXip may be used with a 20% cut-off value in order to reduce the proportion of prostate biopsies by approximately 5%, without missing a single case of cancer. Moreover, higher iXip values are significantly correlated with tumor aggressiveness.