[798] Cohort Design and Localization Is Critical for the Understanding of the Clinical Implications of Prostate Cancer with ERG Rearrangement

M Braun, VJ Scheble, T Wilbertz, AC Stiedl, K Petersen, D Schilling, R Kuefer, F Fend, G Kristiansen, MA Rubin, S Perner. University Hospital of Tuebingen, Tuebingen, Germany; University Hospital of Ulm, Ulm, Germany; University Hospital of Zuerich, Zuerich, Switzerland; Weill Cornell Medical College, New York, NY

Background: TMPRSS2-ERG gene fusions are the most frequent rearrangements in prostate cancer (PCa) with a great variability in its reported prevalence ranging from 15-78% depending on the study cohorts. The reason for this variability in different study cohorts is unknown. The aim of our study was to elucidate the differences in ERG rearrangement prevalence.
Design: We assessed the frequency of ERG rearrangement by FISH in three clinical cohorts. The first cohort comprises the index tumor focus from the peripheral zone of 109 partially PSA-screened prostatectomy samples. The second cohort includes 105 PCa samples incidentally diagnosed by TUR-P, and the third cohort includes 71 PCa samples incidentally identified in the course of cystoprostatectomy. Within the cystoprostatectomy PCa cases, 9 cases had tumor foci within the transition zone.
Results: Out of 109 prostatectomy samples, 49.5% harbored the ERG rearrangement. 29.5% of the PCa cases incidentally identified by TUR-P and 33.8% of the PCa cases incidentally detected in the course of cystoprostatectomy revealed ERG rearrangement. Of note, 32.2% of the PCa cases diagnosed by TUR-P and 23.8% of the PCa identified in cystoprostatectomy specimen showed interfocal heterogeneity with regard to the rearrangement status. Two of the 9 (22.2%) transition zone PCa foci revealed the ERG rearrangement. Overall, the prostatectomy cohort had a higher Gleason grade as compared to the incidentally diagnosed cohorts.
Conclusions: We compared the ERG rearrangement frequency in incidentally detected cohorts and a prostatectomy PCa cohort. We could confirm that the ERG rearrangement appears in approximately half of the cases in the prostatectomy cohort but was observed significantly less frequently in incidentally diagnosed PCa cohorts. Our observations support the hypothesis that the ERG rearrangements may be more frequent in peripheral zone tumors than transition zone tumors, a finding consistent with the potentially more aggressive nature of TMPRSS2-ERG fusion PCa cases.
Category: Genitourinary (including renal tumors)

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 128, Wednesday Afternoon


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