The prognostic impact of a negative confirmatory biopsy and mpMRI in men on active surveillance for prostate cancer
Keyan Salari, MD, Jeffrey Twum-Ampofo, MD, Andrew Gusev, MD, Joshua Caldwell, MD, Edouard Nicaise, BS, David Kuppermann, MD, Dimitar Zlatev, MD, Douglas Dahl, MD, Jason Efstathiou, MD, Phil, Michael Blute, MD, Anthony Zietman, MD, Adam Feldman, MD, MPH.
Massachusetts General Hospital, Boston, MA.
PURPOSE: Active surveillance (AS) is increasingly used in managing low-risk and favorable intermediate-risk prostate cancer. To mitigate the risk of unsampled higher risk disease, most institutional AS protocols call for a multiparametric MRI of the prostate (mpMRI) and a confirmatory prostate biopsy within 12-18 months following initial diagnostic biopsy. Here, we investigate whether the results of confirmatory biopsy and mpMRI impact the outcomes of men on AS.
MATERIALS AND METHODS: We retrospectively reviewed our institutional database of men enrolled in AS between 1997-2019 who underwent a confirmatory biopsy within 18 months of diagnosis and ≥3 biopsies overall. Patients who progressed to treatment on the basis of their confirmatory biopsy were excluded. Biopsies containing prostate cancer were considered positive. Biopsies containing only benign prostatic tissue, prostatic intraepithelial neoplasia (PIN), or atypical small acinar proliferation (ASAP) were considered negative. A PI-RADS v2 score of 3 or higher was considered a positive mpMRI. The primary outcome was biopsy progression-free survival and secondary outcomes included grade- and volume-related biopsy progression-free survival, biochemical recurrence, and metastasis-free survival. Statistical analysis was conducted using the Kaplan-Meier method and Cox proportional hazards regression.
RESULTS: Out of 1268 patients in our cohort, 470 met inclusion criteria for this analysis, with a median follow up of 7.2 years. At diagnosis, median age was 63 years (IQR 58-68) and median PSA was 4.9 ng/mL (IQR 3.7-6.5). The vast majority of patients had grade group 1 (99%) and clinical stage T1 (95%) disease. A total of 177 patients (38%) had a negative confirmatory biopsy. Of the 470 patients, 38% progressed to treatment, with biopsy (grade- or volume-based) progression the most common reason (87%). In univariate analysis, a negative confirmatory biopsy and a negative initial mpMRI were each significantly associated with improved biopsy progression-free survival, while age of diagnosis, involvement of >20% of any core on diagnostic biopsy, and PSA density ≥0.15 were associated with greater risk of biopsy progression. In multivariate analysis, a negative confirmatory biopsy remained a significant predictor of grade-based (but not volume-based) biopsy progression-free survival (HR 0.54 [95%CI 0.31-0.95], P = 0.03), whereas mpMRI status was no longer a significant predictor. Neither confirmatory biopsy nor mpMRI status were associated with biochemical recurrence or metastasis-free survival.
CONCLUSIONS: A negative confirmatory biopsy is associated with a significantly lower rate of subsequent grade reclassification and progression to treatment among men on AS. This may serve as a useful tool for prognostication and help determine the intensity of interval biopsies for men on AS.
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