[743] TMPRSS2-ERG Fusion Is Frequently Observed in Gleason Pattern 3 Prostate Cancer in a Canadian Cohort

AD Darnel, CJ LaFargue, RT Vollmer, J Corcos, TA Bismar. McGill University and Jewish General Hospital, Montreal, QC, Canada; Weill Cornell Medical College, NY; VA and Duke University Medical Centers, Durham, NC; McGill University, Montreal, QC, Canada; University of Calgary, Calgary, AB, Canada

Background: TMPRSS2-ERG gene fusion was recently reported as the most common gene rearrangement in prostate cancer (PCA). However, its significance as a prognostic marker for clinical practice beyond current pathological staging is still needs to be validated in larger cohorts.
Design: Using break-apart FISH assay to indirectly assess the fusion of TMPRSS2-ERG. We sought to characterize the incidence, pathological features and clinical parameters of TMPRSS2-ERG gene fusion in a cohort of 196 Canadian men treated by radical prostatectomy for localized PCA, and to investigate its potential as a biomarker in PCA.
Results: In this cohort 163/196 prostate samples were available for evaluation by FISH. 41% of the patients showed positive gene fusion status in their PCA. The TMPRSS2-ERG gene fusion status was homogenous within the same cancer focus and 82% of fusion positive PCA were present in GS 6 or 7 vs. 14% in GS 8 (p= 0.004). Moreover, TMPRSS2-ERG fusion was present in 42% of Gleason pattern 3 vs. 27% of Gleason pattern 4 (p = 0.014). However, in this study, no significant association was noticed between TMPRSS2-ERG fusion status in relation to pathological stage, surgical margin or biochemical failure.
Conclusions: The significance of TMPRSS2-ERG gene fusion as a prognostic marker for men with localized prostate cancer beyond current pathological staging needs further investigation. The higher association of TMPRSS2-ERG with Gleason score 6 and 7 should be further validated. This finding could have significant clinical impact in further stratifying patients with PCA should the TMPRSS2-ERG be confirmed as prognostic marker linked to worse clinical outcome.
Category: Genitourinary (including renal tumors)

Monday, March 9, 2009 1:00 PM

Poster Session II # 106, Monday Afternoon