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Secular trends in prostate biopsy criteria and outcomes: The Dartmouth experience
Lael Reinstatler, MD, MPH, Cody M. Rissman, MD, John D. Seigne, MB, Elias S. Hyams, MD.
Dartmouth Hitchcock Medical Center, Lebanon, NH, USA.

BACKGROUND: More restrictive prostate specific antigen (PSA) screening guidelines issued in 2012 have led to lower rates of screening nationwide, as well as lower rates of prostate cancer diagnosis across risk categories. It is not known, however, how guidelines may have affected regions with less aggressive a priori screening practices. Dartmouth-Hitchcock Medical Center (DHMC) is a large academic center within the hospital referral region (HRR), or regional healthcare market, with the lowest rate of PSA screening among Medicare patients in 2012. We evaluated the impact of changed screening guidelines on biopsy and diagnosis of prostate cancer at DHMC to determine secular trends at an institution with low baseline screening rates. METHODS: Using a data warehouse query and chart review, we retrospectively analyzed all patients at DHMC who underwent a trans-rectal ultrasound guided (TRUS) prostate biopsy January 2011 through March 2016. We excluded patients on active surveillance and those with clinical metastatic disease. Demographic and clinical characteristics were collected and analyzed, stratifying on time. Multivariable analysis was conducted using a priori variables to assess for factors associated with higher grade cancer diagnoses. Statistical analysis was performed using SAS 9.4 (Cary, NC). RESULTS: During the study period, 614 prostate biopsies were performed. The mean age at biopsy was 63.7 (42-87) and the mean PSA was 8.2 (0.14-49.9). Pathology results included 276 (44.9%) benign, 104 (16.9%) Gleason 3+3, and 234 (38.1%) with ≥3+4 disease. When analyzed by year, the mean PSA at biopsy increased with time (7.2 in 2011 vs 10.1 in 2016; p = 0.0085), while mean age did not. The proportion of benign results remained stable (46.1% in 2011 vs 45.8% in 2015), however the proportion of low grade disease decreased while intermediate/high grade disease increased (2011 vs 2015: 21.1% vs 10.8% Gleason 3+3, 32.9% vs 43.3% ≥Gleason 3+4, p = 0.0454). On multivariable analysis comparing low grade (Gleason 3+3) to intermediate/high grade disease, factors predictive of worse disease included abnormal digital rectal exam (OR 2.19, p-value 0.0076), higher PSA level (OR 1.09, p-value 0.0040), and later biopsy date (OR 1.01, p-value 0.0469). CONCLUSIONS: In an environment of already conservative screening practices, there has been a shift in both prostate biopsy criteria and outcomes post-2012, namely a rising PSA threshold for biopsy and a 50% decrease in the rate of diagnosis of low grade disease. There has been a concomitant increase in the rate of higher grade disease by 30%. These trends demonstrate the potential benefit of more restrained screening and biopsy practices, even in regions with low baseline screening rates. Additional study of the downstream effects of changing screening and biopsy practices is needed to ensure these are favorably impacting the overall quality of care.

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