Can Confirmatory Biopsy be Omitted in Patients with Prostate Cancer Favorable Diagnostic Features on Active Surveillance?

Prassannah Satasivam, Bing Ying Poon, Behfar Ehdaie, Andrew J. Vickers, James A. Eastham

We evaluated whether initial diagnostic parameters could predict the confirmatory biopsy result in patients initiating active surveillance for prostate cancer, to determine whether some men at low risk of reclassification could be spared unnecessary biopsy. The cohort included 392 men with Gleason 6 prostate cancer on initial biopsy undergoing confirmatory biopsy. We used univariate and multivariable logistic regression to assess if high-grade cancer (Gleason ≥ 7) on confirmatory biopsy could be predicted from initial diagnostic parameters (prostate-specific antigen density, magnetic resonance imaging result, percent positive cores, percent cancer in positive cores, and total tumor length). Median age was 62 years (IQR 56-66) and 47% of patients were found to have a dominant or focal lesion on magnetic resonance imaging. Of the 392 patients, 44 (11%) were found to have high-grade cancer on confirmatory biopsy, among whom 39 had 3+4, 1 had 4+3, 3 had Gleason 8, and 1 patient had Gleason 9 disease. All predictors were significantly associated with high-grade cancer at confirmatory biopsy on univariate analysis. However, in the multivariable model only prostate-specific antigen density and total tumor length were significantly associated (AUC of 0.85). Using this model to select patients for confirmatory biopsy would generally provide a higher net benefit than performing confirmatory biopsy in all patients, across a wide range of threshold probabilities. If externally validated, a model based on initial diagnostic criteria could be used to avoid confirmatory biopsy in many patients initiating active surveillance.