Predicting Gleason Group Progression for Men on Prostate Cancer Active Surveillance: Role of a Negative Confirmatory Magnetic Resonance Imaging-Ultrasound Fusion Biopsy

Purpose: Active surveillance has gained acceptance as an alternative to definitive therapy in many men with prostate cancer. Confirmatory biopsies to assess the appropriateness of active surveillance are routinely performed and negative biopsies are regarded as a favorable prognostic indicator. We sought to determine the prognostic implications of negative multiparametric magnetic resonance imaging-transrectal ultrasound guided fusion biopsy consisting of extended sextant, systematic biopsy plus multiparametric magnetic resonance imaging guided targeted biopsy of suspicious lesions on magnetic resonance imaging. Materials and Methods: All patients referred with Gleason Grade Group 1 or 2 prostate cancer based on systematic biopsy performed elsewhere underwent confirmatory fusion biopsy. Patients who continued on active surveillance after a positive or a negative fusion biopsy were followed. The baseline characteristics of the biopsy negative and positive cases were compared. Cox regression analysis was used to determine the prognostic significance of a negative fusion biopsy. Kaplan-Meier survival curves were used to estimate Grade Group progression with time. Results: Of the 542 patients referred with Grade Group 1 (466) or Grade Group 2 (76) cancer 111 (20.5%) had a negative fusion biopsy. A total of 60 vs 122 patients with a negative vs a positive fusion biopsy were followed on active surveillance with a median time to Grade Group progression of 74.3 and 44.6 months, respectively (p < 0.01). Negative fusion biopsy was associated with a reduced risk of Grade Group progression (HR 0.41, 95% CI 0.22-0.77, p < 0.01). Conclusions: A negative confirmatory fusion biopsy confers a favorable prognosis for Grade Group progression. These results can be used when counseling patients about the risk of progression and for planning future followup and biopsies in patients on active surveillance.