Prevalence and prognostic significance of TMPRSS2-ERG gene fusion in lymph node positive prostate cancers

BACKGROUNDTMPRSS2-ERG gene fusion is the most frequent genetic alteration in prostate cancer. However, information about its distribution in lymph node positive prostate cancers and the prognostic significance in these advanced tumors is unknown. METHODSGene fusion status was determined by fluorescence in situ hybridization on a tissue-microarray constructed from 119 hormone-naive nodal positive, surgically treated prostate cancers containing samples from the primary tumors and corresponding lymph node metastases. Data were correlated with various tumor features (Gleason score, stage, cancer volume, nodal tumor burden) and biochemical recurrence-free, disease-specific, and overall survival. RESULTSTMPRSS2-ERG fusion was detected in 43.5% of the primary tumors. Conversely, only 29.9% of the metastasizing components showed the fusion. Concordance in TMPRSS2-ERG status between primary tumors and metastases was 70.9% (Kappa 0.39); 20.9% and 8.1% of the patients showed the mutation solely in their primary tumors and metastases, respectively. TMPRSS2-ERG fusion was not correlated with specific histopathological tumor features but predicted favorable biochemical recurrence-free, disease-specific and overall survival independently when present in the primary tumor (P<0.05 each). CONCLUSIONTMPRSS2-ERG fusion is more frequent in primary prostate cancer than in corresponding metastases suggesting no selection of fusion-positive cells in the metastatic process. The gene fusion in primary tumors independently predicts favorable outcome. Prostate 74: 1647-1654, 2014. (c) 2014 Wiley Periodicals, Inc.