ObjectivesRecent studies have demonstrated that up-front docetaxel combined with androgen deprivation therapy (ADT) prolongs survival in some patients with metastatic hormone-naïve prostate cancer (mHNPC). However, new biomarkers for selecting personalized treatment strategies for mHNPC are warranted. We evaluated the value of low-molecular-weight protein tyrosine phosphatase (LMW-PTP) expression as a prognosticator in men with mHNPC. Methods and materialsA total of 48 men with mHNPC diagnosed from 2003 to 2009 were enrolled in this study. Prostate cancer tissues obtained by needle biopsies were immunohistochemically stained for LMW-PTP. Correlations between LMW-PTP expression and clinicopathological characteristics were then assessed. ResultsAt the time of analysis, 29 (60.4%) patients were alive, whereas 15 (31.3%) and 4 (8.3%) died of prostate cancer and nonprostate cancer, respectively. Of these, 29 (60.4%) had low LMW-PTP expression and 19 (39.6%) had high expression. Median overall survival (OS) for patients with high LMW-PTP expression was not reached and that for patients with low LMW-PTP expression was 23.8 months. High LMW-PTP expression was significantly correlated with a shorter OS compared with low LMW-PTP expression (P = 0.01). Moreover, multivariate analysis showed that Gleason score (≥8 vs.≤7; HR = 5.8, 95% CI: 1.3–26.5, P = 0.02) and LMW-PTP expression (high vs. low; HR = 2.7, 95% CI: 1.0–7.2, P = 0.04) were independent prognostic factors for OS. ConclusionsLMW-PTP is a potential biomarker to predict OS in patients with mHNPC.