The prognostic and predictive value of TMPRSS2-ERG gene fusion and ERG protein expression in prostate cancer biopsies.

The thesis has demonstrated that assessment of ERG protein expression is feasible in biopsy specimens, and a high concordance was found between the IHC assay and FISH assessment of ERG rearrangement. The low proportion of ERG reclassification between biopsies and prostatectomies supports the use of ERG assessment in biopsies to characterise the individual patient's ERG status. ERG status harbours important prognostic value in terms of tumour progression for patients managed on AS, whereas ERG expression has no predictive value for ADT response in men with advanced PCa undergoing first-line castration-based ADT. The overall conclusion of the thesis is that ERG protein expression provides valuable prognostic information in low-risk PCa managed observationally, and ERG expression might be used to personalise follow-up regimens in future AS programmes.