The role of HER2 in prostate cancer progression is still debated, with divergent reports about the level of HER2 expression in HRPC (Reese et al, 2001; Shi et al, 2001; Di Lorenzo et al, 2002; Fossa et al, 2002; Mendoza et al, 2002; Savinainen et al, 2002; Calvo et al, 2003; Hernes et al, 2004). This evidence concerns the gene ERBB2 and prostate cancer.