To assess the role of confirmatory prostate biopsy in the accurate risk assessment of patients with low risk prostate cancer eligible for active surveillance.

Patients electing active surveillance of their low grade, low volume prostate cancer with prostate-specific antigen <20 ng/mL, <cT2 disease who underwent confirmatory rebiopsy were included. Biopsy progression was defined as >2 core involvement or Gleason 7 disease on subsequent biopsies. Prostate-specific antigen, total number of cores on initial and rebiopsy, the presence of high-grade prostatic intraepithelial neoplasia, and prostate-specific antigen density, when available, were assessed as predictors of biopsy progression.

Sixty patients were included. Median time to rebiopsy was 2 months. Nineteen patients (31.7%) had findings that excluded them from active surveillance. Despite rebiopsy findings, 7 patients elected for active surveillance, all of which eventually underwent treatment for continued biopsy progression. Of the 41 patients eligible for active surveillance after rebiopsy, 8% elected treatment, 74% remained on active surveillance, and 13% experienced biopsy progression. No cancer on rebiopsy was associated with a reduced risk of progression to treatment on active surveillance (odds ratio 0.14, P = .011). A microfocus of Gleason 4 pattern (odds ratio 16.0, P = .04) and high-grade prostatic intraepithelial neoplasia (odds ratio 7.29, P = .03) on initial biopsy were independent predictors of immediate rebiopsy progression. Prostate-specific antigen, prostate-specific antigen density, and the total number of cores were not significant.

Confirmatory rebiopsy aids in the accurate identification of low-risk patients for active surveillance as one-third are initially undergraded. Patients with high-grade prostatic intraepithelial neoplasia and any Gleason pattern 4 on initial biopsy are at highest risk and should be counseled regarding the risks of progression on active surveillance accordingly.