Overexpression of Periostin in Tumor Biopsy Samples Is Associated With Prostate Cancer Phenotype and Clinical Outcome.

BACKGROUND:Overexpression of periostin (POSTN) is associated with prostate cancer (PCa) aggressiveness. We investigated the prognostic significance of POSTN expression in tumor biopsy samples of patients with PCa. METHODS:We scored POSTN expression by immunohistochemistry analysis on 215 PCa biopsy samples using an anti-POSTN-specific antibody. A total immunoreactive score (T-IRS) was calculated by adding the POSTN staining scores of stromal and epithelial tumor cells. Prostate-specific antigen (PSA) progression/recurrence-free survival (PFS), radiographic progression/recurrence-free survival (rPFS), and overall survival (OS) were the study end points. RESULTS:A total of 143 patients received therapy with radical attempt, whereas 72 had locally advanced or metastatic disease and received hormone therapy alone. Median T-IRS was 9 and 12 (range, 0-20), respectively (P = .001). Overall, we found a weak positive correlation of T-IRS with prebiopsy PSA levels (r = 0.166, P = .016) and Gleason score (r = 0.266, P < .000). T-IRS ≥ 8 independently predicted for shorter PSA-PFS and OS (hazard ratio [HR] [95% confidence interval (CI)] ≥ 8 versus < 8: 1.50 [1.06-2.14], P = .024 and 1.92 [1.20-3.07], P = .007, respectively). In the subgroup analysis, the association between T-IRS and patient outcome was retained in patients who received therapy with radical attempt (HR [95% CI] ≥ 8 vs. < 8: rPFS: 2.06 [1.18-3.58], P = .01; OS: 2.36 [1.24-4.50], P = .009) and in those with low to intermediate Gleason scores (HR [95% CI] ≥ 8 vs. < 8: PSA-PFS: 1.65 [1.06-2.59], P = .028; rPFS: 2.09 [1.14-3.87], P = .018; OS: 2.57 [1.31-5.04], P = .006). CONCLUSION:POSTN T-IRS on PCa biopsy samples independently predicted the risk of recurrence, progression, and death in patients with localized disease and in those with low to intermediate Gleason scores.