Utility of RhoC and ZAG protein expression as biomarkers for prediction of PSA failure following radical prostatectomy for high grade prostate cancer.

Aims: To assess the prognostic utility of semi-quantiative expression of RhoC protein in whole prostates from patients who had radical prostatectomies for high grade prostate cancer (PCa).

Methods: Subjects who had surgery >55 months previously with primary Gleason pattern 4 PCa were identified from practice records, archival tissues were retrieved for review and RhoC immunohistochemistry, and ZAG expression was also assessed as a control.

Results: Eighty-nine subjects were included in the study; 57 had a rising prostate specific antigen (PSA) post-operatively ('cases') and 32 did not ('controls'). By univariate analysis, expression of both RhoC and ZAG proteins was greater in controls than cases, but this was significant only for ZAG. By multivariate analysis, Gleason variables (patterns and score), extraprostatic extension and decreased RhoC staining all contributed to predicting PSA failure (p < 0.05). ZAG expression was inversely correlated with Gleason pattern and hence was not independently predictive in our multivariate model.

Conclusions: Increased RhoC expression predicted a good outcome after radical prostatectomy. ZAG staining also correlated with a favourable outcome but was not independently predictive due to its relationship with Gleason pattern.