Evaluation of an Epigenetic Assay for Predicting Repeat Prostate Biopsy Outcome in African American Men.

OBJECTIVE: To evaluate an epigenetic assay performed on tissue from negative prostate biopsies in a group of African American (AA) men undergoing repeat biopsy, and to compare accuracy for predicting repeat biopsy outcome to prior studies conducted in predominantly Caucasian populations. MATERIALS AND METHODS: The study population consisted of 211 AA men from 7 urology centers across the United States; all of whom were undergoing 12-core transrectal ultrasound-guided repeat biopsy within 30 months from a negative index biopsy. All biopsy cores from the negative index biopsy were profiled for the epigenetic biomarkers GSTP1, APC, and RASSF1 using ConfirmMDx for Prostate Cancer (MDxHealth, Irvine, CA). RESULTS: Upon repeat biopsy, 130 of 211 subjects (62%) had no prostate cancer (PCa) detected and 81 of 211 (38%) were diagnosed with PCa. Of the subjects with PCa, 54 (67%) were diagnosed with Gleason score (GS) ≤6 PCa and 27 (33%) with GS ≥7 disease. For detection of PCa at repeat biopsy, ConfirmMDx sensitivity was 74.1% and specificity was 60.0%, equivalent to prior studies (P = .235 and .697, respectively). For detection of GS ≥7 PCa, sensitivity was 78% and specificity was 53%. The negative predictive values for detection of all PCa and GS ≥7 PCa were 78.8% and 94.2%, respectively. CONCLUSION: In this group of AA men, we successfully validated an epigenetic assay to assess the need for repeat biopsy. Results were consistent with previous studies from predominantly Caucasian populations. Therefore, the ConfirmMDx assay is a useful tool for risk stratification of AA men who had an initial negative biopsy.

Effect of stone motion on in vitro comminution efficiency of Storz Modulith SLX.

BACKGROUND AND PURPOSE: During SWL, stone motion secondary to ventilatory motion can be as much as 50 mm. This is much larger than the 4- to 15-mm diameter of the focal regions on most clinical machines. The goal of this study was to determine the effect of stone motion on the fragmentation efficiency of a clinical lithotripter with a small (4-mm) focal spot. MATERIALS AND METHODS: A model stone (6.5 x 7.5 mm) made of gypsum cement was used as an in vitro target for a Storz Modulith SLX lithotripter with a custom-designed waterbath. A motorized positioner was used to translate the stone in order to simulate ventilatory motion. The excursion was variable up to 48 mm (+/- 24 mm about the focus). After treatment by 400 shockwaves, the remnants (> 2 mm) were dried and weighed. RESULTS: Fragmentation efficiency was reduced (P < 0.05) for motion of > or = 10 mm. Similar results were found with different energy levels and firing rates. The reduction in fragmentation efficiency was consistent with calculations of the time the stone was outside the focal region. CONCLUSIONS: Clinically relevant stone motion has a dramatic effect on in vitro comminution. Motion of 10 mm led to a significant reduction in comminution, and for motion > 20 mm, it appeared that three-quarters of the shockwaves missed the stone. These data imply that ventilatory gating or stone tracking may result in fewer shockwaves being required for successful treatment with this lithotripter.