The Prognostic Impact of a Negative Confirmatory Biopsy in Men on Active Surveillance for Prostate Cancer
Keyan Salari, MD, PhD1, Dimitar V. Zlatev, MD1; David Kuppermann, MD1; Mark A. Preston, MD, MPH2; Douglas M. Dahl, MD1; Jason A. Efstathiou, MD, DPhil1; Michael L. Blute, MD1; Anthony L. Zietman, MD1; Adam S. Feldman, MD, MPH1
1Massachusetts General Hospital, Boston, MA; 2Brigham and Women's Hospital, Boston, MA
BACKGROUND: 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 confirmatory prostate biopsy within 12-18 months following initial diagnostic biopsy. Here, we investigate whether the results of confirmatory biopsy impact the outcomes of men on AS.
METHODS: We retrospectively reviewed our institutional database of men enrolled in AS between 1997-2014 who underwent a confirmatory biopsy within 18 months of diagnosis and ≥3 biopsies overall. Thus, 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. Statistical analysis was conducted using the Kaplan-Meier method and Cox proportional hazards regression.
RESULTS: Out of 974 patients in our cohort, 270 met inclusion criteria for this analysis, with a median follow up of 5.4 years. At diagnosis, median age was 64 years (IQR 59-69) and median PSA was 4.8 ng/mL (IQR 3.5-6.2). The vast majority of patients had Gleason ≤6 (98.1%) and clinical stage T1 (94%) disease. A total of 101 patients (37%) had a negative confirmatory biopsy (72 benign, 17 PIN, and 12 ASAP). Of the 270 patients, 28% progressed to treatment, with pathologic progression the most common reason (80%). Univariate predictors of progression to treatment included initial Gleason group, involvement of >20% of any core on diagnostic biopsy, PSA density ≥0.15, and confirmatory biopsy status. In multivariate analysis, a negative confirmatory biopsy remained the strongest predictor of progression to treatment (HR 0.35 [95%CI 0.15-0.81], P = 0.1). Confirmatory biopsy status was not associated with risk of adverse pathology on RP, metastasis-free survival, disease-specific survival, or overall survival.
CONCLUSIONS: A negative confirmatory biopsy is associated with a significantly lower rate of subsequent 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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