Assessment of TMPRSS2:ERG (T:E) Gene Fusion in Prostatic Adenocarcinomas with Mixed Acinar (PCA-A) and Ductal (PCA-D) Components: Comparison of ERG Break-Apart and T:E Fusion Probes
C Sherer, K Cieply, A Liang, A Perepletchikov, A Parwani, R Dhir, T McHale, J Salvatore, L Niemeier, S Bastacky. University of Pittsburgh, Pittsburgh, PA
Background: T:E fusion is present in many PCAs. Most studies have used an ERG break-apart probe to assess ERG disruption as a surrogate marker of T:E fusion. A T:E fusion probe assay is now available to directly assesses T:E fusion. The aim of this study was to compare both methods in pts with PCA (A+D).
Design: Formalin-fixed, paraffin-embedded sections from 19 PCA pts and 9 organ donor prostates (ODP) were obtained from the tissue bank of the University of Pittsburgh. Dxs were confirmed prior to ERG and T:E FISH. All pts had PCA (A+ D) on initial bxs (n=5) or resections (n=14), and some had benign prostate tissue (BPT). PCA-A, PCA-D, and BPT were targeted. Dual-color FISH using either a break-apart probe for ERG disruption or separate probes assessing T:E fusion were compared. Cases were positive if > 20% of cells had ERG disruption or T:E fusion, with thresholds based on ODPs.
|PCA (A or D)||PCA-A||PCA-D||PCA (A+D)||BPT|
|ERG (+/total cases (%))||14/19 (74%)||9/16 (56%)||14/19 (74%)||9/16 (56%)||3/10 (30%)*|
|TE (+/total cases (%))||15/19 (79%)||11/17 (65%)||9/15 (60%)||7/11 (64%)||0/18 (0%)|
|p-value||> 0.05||> 0.05||> 0.05||> 0.05||> 0.05|
|3+4=7||4/6 (67%)||4/6 (65%)||p>0.05|
|4+3=7||6/8 (75%)||8/8 (100%)*||p>0.05|
|4+4=8||3/4 (75%)||3/4 (75%)||p>0.05|
|4+5=9||1/1 (100%)||1/1 (100%)||p>0.05|