[986] TMPRSS2-ERG Gene Fusion Status in Salvage Radical Prostatectomy Specimens Following Radiotherapy

M Stanton, CC Guo, X Li, Y Wang, L Andino, IN Prokhorova, LL Pisters, P Troncoso. The University of Texas MD Anderson Cancer Center, Houston, TX

Background: A common chromosomal rearrangement leading to the fusion of the TMPRSS2 and ERG genes has been identified in a majority of untreated prostate cancer cases. Information regarding TMPRSS2-ERG gene fusion in recurrent prostate cancer following radiotherapy is limited.
Design: We reviewed 50 radical prostatectomy specimens (RPS) from patients who underwent salvage radical prostatectomy after radiotherapy between 1993-2008. Twenty-five cases have been analyzed to date for TMPRSS2-ERG gene fusion by fluorescence in situ hybridization using ERG break-apart probes.
Results: Median overall patient age was 68 years (range 45-75 years). Median interval between radiation therapy and surgery was 4 years (range 1-13 years). Median pre-salvage serum PSA was 3.40 ng/mL (range <0.1-39.20 ng/mL). The Gleason score was ≤7 (4+3) in 17 and ≥8 in 24 cases. Therapy effect precluded grading in 9 cases. The pathologic stage was pT2: 23; pT3a: 7 and pT3b: 20. Eight patients had lymph node metastases. The tumors were unifocal in 33/50 cases (66%) and multifocal in 17/50 cases (34%). Median total tumor volume was 1.27 cc (range 0.05-12.96 cc). Of the 25 cases analyzed thus far (17 unifocal tumors, including 2 with corresponding nodal metastases, and 8 multifocal tumors), 10 (40%) were positive for the ERG gene rearrangement. In 9 of the cases, the rearrangement was associated with deletion of the 5' ERG gene. In the 8 multifocal tumors, the dominant focus was analyzed in 5 cases, and all foci were analyzed in 3 cases (2 foci in 2 cases; 3 foci in 1 case). The two primary tumors with lymph node metastases were positive, and there was concordance of the ERG gene fusion status between the primary tumors and the nodal metastases. ERG gene rearrangement was not detected in any of the foci studied in 3 multifocal tumors.
Conclusions: Recurrent prostate cancer following radiotherapy exhibits TMPRSS2-ERG gene rearrangement in the range observed in untreated tumors.
Category: Genitourinary (including renal tumors)

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 123, Wednesday Afternoon

 

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