Assessing expression of MUC1 and ZAG protein biomarkers in prostate biopsies improves prediction of adverse pathology following radical prostatectomy

Objectives: To determine whether assessing expression of MUC1 and ZAG proteins in prostate biopsies, by immunohistochemistry, improves prediction of radical prostatectomy histopathology, which in turn predicts longer-term outcomes. Methods: We studied 231 consecutive patients managed by two experienced urologic surgeons (MF, LH). Each patient had prostate biopsies revealing cancer followed by a radical prostatectomy. Expression of MUC1 and ZAG in biopsy tissue was assessed by immunohistochemistry, masked to the radical prostatectomy histopathology. Data were analysed by Chi-square, Fischer exact test & Mann Whitney U test followed by multivariate analysis using binary logistic regression. Results: By univariate analysis, MUC1 expression in prostate biopsies was associated with worse histopathology in the radical prostatectomy specimen (p<0.023), while ZAG expression was associated with better pathology (p=0.03). By multivariate analysis decreased expression of ZAG in biopsies (p=0.02), but not MUC1 expression, improved prediction of high-risk radical prostatectomy pathology beyond conventional biopsy variables; neither MUC1 nor ZAG staining improved prediction of minimal-risk cancers. Conclusions: Assessment of ZAG expression in prostate biopsies, and possibly MUC1 expression, may improve knowledge of prostate cancers in vivo or after radical prostatectomy.