The prognostic role of ERG immunopositivity in prostatic acinar adenocarcinoma: a study including 454 cases and review of the literature.

TMPRSS2/ERG fusion is among the most frequent genetic anomalies in prostate adenocarcinomas. Although positive immunostaining for ERG has been shown to tightly correlate with ERG fusion status, the clinical and prognostic significance of a positive ERG stain remains undetermined. The significance of ERG immunostaining in 454 consecutive prostate adenocarcinomas from radical prostatectomies (RPs) using tissue microarrays, herein, is evaluated. A separate set of 59 cases of incidental prostate adenocarcinoma detected on transurethral resection of prostate with a Gleason score of 6 was also included. ERG translocation was significantly more common in peripheral zone cancer in comparison with cancer of the transitional zone (33% in RP versus 5% in transurethral resection of prostate specimens). In the RP cohort, although ERG positivity was significantly associated with younger age at presentation and lower prostate-specific antigen values, it showed no association with Gleason score or with pathologic stage. In multivariate analysis, biochemical recurrence was only associated with the final RP Gleason score and elevated prostate-specific antigen levels and was unrelated to neither ERG positivity or to its staining intensity. In our hands, ERG positivity was unrelated to either aggressive local tumor characteristics or a worse outcome. Our results, as well as an extensive review of the related literature showing conflicting findings, seem to indicate that ERG immunopositivity cannot be considered as an important prognostic factor in prostate cancer.