Prognostic value of periostin in early-stage breast cancer treated with conserving surgery and radiotherapy.

The present study was performed to explore the prognostic significance of periostin expression in a cohort of patients with early-stage breast cancer treated with breast conserving surgery following radiotherapy. A tissue microarray of tumor samples from 259 patients with early-stage breast cancer was assayed for periostin, estrogen receptor (ER), progesterone receptor (PR), ErbB2 receptor tyrosine kinase 2 and Ki-67 expression by immunohistochemistry. The association of periostin with other clinicopathological parameters and clinical outcomes, including local recurrence free survival (RFS), distant metastasis free survival (DFS) and overall survival (OS), were assessed through log-rank tests and univariate and multivariate analysis. Periostin expression was identified in 91 of the 259 tissue samples (35%). The periostin status was significantly associated with histological grade (P=0.001), nodal status (P=0.023), molecular subtype (P<0.01), ER status (P<0.01), PR status (P<0.01) and Ki-67 expression (P=0.011). Furthermore, periostin expression was associated with an increased risk of five-year local recurrence (95.8% vs. 89.0%; P=0.017) and distant metastasis (92.3% vs. 79.1%; P=0.001) in patients with early stage breast cancer. Multivariate analysis using Cox's proportional hazards model demonstrated that periostin expression was an independent predictor of all clinical outcomes in breast cancer (RFS, P=0.018; DFS, P=0.025; OS, P=0.047). Therefore, it was concluded that periostin is associated with an increased risk of local relapse and distant metastasis in early-stage breast cancer treated with conserving surgery and radiotherapy. This association should be further investigated in larger cohorts to validate the clinical significance of periostin expression.