Updated project metadata. Purpose: Prostate cancer is the most frequently diagnosed cancer in men and the third leading cause of cancer related deaths among men living in developed countries. Biomarkers that predict disease outcome at the time of initial diagnosis would aid management of the disease. Experimental design: Proteins extracted from formalin-fixed paraffin-embeddded sections were identified either using LC-MALDI MS/MS of tryptic digests or after separation by one- or two-dimensional electrophoresis. A list of potential biomarker candidates, based on proposed associations with prostate cancer, was derived from the 320 identified proteins. Results: Four of the candidates: annexin A2, peroxiredoxin-1, prostate-specific antigen and zinc-alpha-2-glycoprotein, were examined by Western blotting of extracts of biopsies from men whom there was 10-year disease outcome data. Multiplexed Western blotting using cocktails of antibodies and fluor-labeled detection reagents showed that annexin A2 provided the best prediction of risk of metastatic disease. Conclusions and clinical relevance: This pilot study indicates that tumour expression of ANXA2 in diagnostic biopsies of a prostate cancer is predictive for the metastatic potential of that cancer. The potential of protein profiling of each cancer is to lead to an overall reduction in mortality from metastatic prostate cancer as well as reduced treatment associated morbidity.