ERG Protein Expression Is of Limited Prognostic Value in Men with Localized Prostate Cancer

Background. The prognostic significance of ERG expression in prostate cancer (PCA) has generated mixed results. We sought to investigate the prognostic significance of ERG expression in a localized cohort of men with PCA. Material and Methods. We investigated ERG protein expression in a cohort of 198 men with localized PCA. ERG expression was correlated with patients' clinical outcome and several pathological parameters, including Gleason score (GS), pathological stage, surgical margin, and extra-capsular extension. Results. ERG expression was detected in 86/198 (43.4%) patients exclusively in neoplastic epithelium. Overall, ERG mean expression intensity was versus in acinar PCA compared to foamy type PCA ( ). In HGPIN, ERG intensity levels were comparable to those in foamy type PCA ( ) but significantly lower than those in acinar PCA ( ). ERG expression was significantly associated with extra-prostatic extension and higher pathological stage and showed a trend toward seminal vesicle invasion. Herein, ERG expression was documented in 50/131 (38.1%) patients with pT2 versus 30/55 (54.5%) patients with pT3 ( ). ERG association with higher pathological stage was more pronounced in patients with . Grouping patients into those with versus 7, there was no significant association between ERG expression and GS. Similarly, no association was present in relation to either surgical margins or postsurgical serum PSA levels. Conclusion. We report significant association between ERG protein levels and extra-prostatic extension and higher pathological stage. ERG expression is not associated with adverse clinical outcome and is of limited prognostic value in localized PCA. 1. Introduction ERG protein expression has been recently suggested to be reflective of ERG gene rearrangements in prostate cancer (PCA) documenting remarkable concordance between the two [1–6]. The rearrangements between the androgen receptor-regulated gene TMPRSS2 (21q22.3) and members of the ETS family member of transcription factor gene, most commonly ERG (21q22.2), are among the most common genetic alterations detected in prostate cancer [7–11]. ERG gene rearrangements have been detected in roughly half (40–60%) of PCA of surgical cohorts compared to a rate of 12%–15% in incidental or watchful waiting cohorts [7, 12–18]. Previous studies investigating the prognostic significance of ERG gene rearrangements have revealed mixed results [19–22]. However, it is becoming more evident that ERG gene rearrangements signify a molecular subtype of PCA. Some studies investigating the significance of ERG