Periostin in ovarian carcinoma: from heterogeneity to prognostic value

Periostin (POSTN), an extracellular matrix protein, is involved in tumor-associated extracellular matrix (ECM) remodeling. However, its potential value as a prognostic and/or predictive factor has not yet been confirmed. The present study aims to assess POSTN expression separately in tumor cells and stroma of different ovarian carcinoma (OC) histological types, and its relationship with clinicopathological features.

102 cases of different histological OC subtypes were immunohistochemically investigated, for POSTN expression assessment in both epithelial tumor cells and tumor stroma. Statistical analysis was performed to correlate POSTN profile with clinicopathological characteristics, therapeutic response, and survival.

POSTN expression in epithelial tumor cells was significantly correlated with POSTN expression in tumor stroma. The expression of POSTN in tumor cells was associated with histological type, tumor type (type I and II), tumor recurrence, progression-free survival (PFS), and overall survival (OS), whereas stromal POSTN expression was significantly correlated with age, histological type, tumor type, grade, and stage, residual disease, tumor recurrence, response to chemotherapy, and OS. Survival analysis revealed significant differences of PFS and OS in patients with high POSTN expression in tumor cells and negative stromal POSTN expression compared to patients with low POSTN expression in tumor cells and positive stromal POSTN expression (PFS: hazard ratio (HR) = 2.11, 95% confidence interval (CI): 1.33-3.37, P = 0.002; OS: HR = 1.78, 95% CI: 1.09-2.89, P = 0.019).

The comparative assessment of POSTN immunoexpression in two tumor compartments: in tumor cells and stroma, by use of different scoring systems revealed that higher stromal POSTN levels are evidently correlated with unfavorable clinical features and poorer prognosis, while POSTN expression in tumor cells seems to be associated with a better patient outcome.