Osteopontin expression in ovarian carcinoma effusions is related to improved clinical outcome

Osteopontin, a soluble protein present in all body fluids, is involved in signaling pathways related to adhesion and extracellular matrix interactions, affecting multiple cellular functions, including inflammation, angiogenesis, and tumor metastasis. We studied osteopontin expression by immunohistochemistry and its clinical relevance in 170 effusions (140 peritoneal, 30 pleural) from women with advanced-stage ovarian carcinoma. Carcinoma cells expressed osteopontin in 126 (74%) of 170 effusions. Osteopontin expression was more frequent in effusions from patients with high-grade tumors (P = .036) but was significantly associated with better debulking at primary surgery (P = .019) and complete response to chemotherapy at diagnosis (P = .021). Osteopontin expression was positively associated to that of the previously studied nuclear factor κB inhibitor IκB (P = .019) and negatively related to expression of the inhibitor of apoptosis family member XIAP (P = .008) and the angiogenic marker endoglin (CD105; P = .018). In univariate survival analysis, the presence of osteopontin in carcinoma cells in primary diagnosis prechemotherapy effusions was associated with longer progression-free survival (P = .037), a finding that did not retain its significance in multivariate Cox analysis. This study demonstrates that osteopontin is frequently expressed in ovarian carcinoma effusions. However, its presence in tumor cells at this anatomical site is unexpectedly associated with less aggressive clinical course, suggesting different and yet undefined biological roles for this protein in serous effusions.