Multiple cores of Gleason score 6 correlate with favourable findings at radical prostatectomy

What's known on the subject? and What does the study add? Previous studies have reported variable outcomes at radical prostatectomy (RP) with Gleason score 6 (GS6) on biopsy. It has been shown that a significant proportion of patients with GS6 disease at biopsy are upgraded to Gleason score 7 or higher after RP, increasing the risk of an adverse outcome. However, such studies have focused on clinical parameters such as PSA, prostate volume and biopsy cancer volume, in concert with GS6, to predict clinically significant upgrading. The present study is the first to use a significant number of patients with the aim of specifically analyzing the outcome at RP (i.e. percentage organ-confined, margin status, overall grade and biochemical recurrence) and making a direct correlation with the number of positive cores to show that the overall prognosis is favourable. Objective To establish whether the good prognosis of Gleason score 6 (GS6) is maintained in the setting of multiple involved cores. Patients and Methods In total, 6156 men (from 1 April 2000 to 30 April 2007) with GS6 on biopsy underwent radical prostatectomy (RP) at our institution. The number of positive cores was correlated with the outcome at RP. Results More positive cores correlated with less organ-confined disease (P < 0.001), positive margins (P < 0.012), increasing RP grade (P < 0.001) and increased seminal vesicles/lymph node involvement (P = 0.012). For men with data available, the actuarial risk of being biochemically free of disease at 5 years was 93.2% when ≤6 cores were positive (812 men followed to 5 years) vs 89.1% if >6 cores were positive (41 men followed to 2 years) (P = 0.6). Although the predicted 'cure rate' of >75% probability of a tumour showing no evidence of biochemical recurrence at 10 years after RP was statistically different between cases with ≤6 vs >6 positive cores (P < 0.0001), the outcome in both groups was still favourable (90.5% vs 84%). Partin-like tables were generated factoring in the number of positive cores to predict organ-confined disease as a guide for urologists to perform nerve-sparing surgery. For example, with T1c disease, there was a ≥75% probability of organ-confined disease with one to three positive cores regardless of prostate-specific antigen (PSA) level, and the same probability was present with four to six positive cores and a PSA level of 0-4 ng/mL. Conclusion A low Gleason score on biopsy is a powerful prognostic finding, such that this favourable outcome is maintained even in the setting of multiple positive cores with GS6.