Osteopontin (OSP) is a metastasis-related gene associated with progression cancers. We assigned osteopontin as potential contributors in breast cancer.
115 de novo metastatic breast cancer (MBC) patients presented by visceral with or without bone metastasis (visceral crisis), brain metastasis was excluded. Patients received first line Docetaxel plus cisplatin and anti Her2 (for Her2 positive) whenever governmental or financial support. Serum osteopontin was measured by ELIZA and osteopontin gene mutation was analyzed by sequencing and correlated with clinicopathological criteria, response, PFS and OS.
High serum OSP was observed in Her2 amplified (mean±SD; 64.4±42.3) followed by TNBC (mean ± SD; 55.9 ± 34.7) then Luminal A and B subtypes (mean±SD; 36.3±32.2) and (mean±SD; 38.3±33.1), respectively (P 0.01). By sequencing technique OSP gene mutation was highly presented in TNBC (85% mutant versus 15% OSP non mutant) followed by Her2 amplified (80% mutant versus 20% OSP non mutant) then luminal B (61.9% mutant versus 38.1% OSP non mutant) and luminal A (57.9% mutant versus 42.1% OSP non mutant). High serum lOSP was significantly correlated with disseminated visceral and bone metastasis (P 0.03). Both high serum OSP level and OSP gene mutation showed same poor PFS (median, 12 months vs. 14 months; P = 0.001) and poor OS (median, 14 months vs. 18 months; P = 0.001). Patients with mutant OSP demonstrated poor response (74% of SD & progressed diseases were mutant versus 26% were non mutant OSP, P 0.04). Also, high pretreatment serum OSP level was associated with poor response (mean±SD for stable & progressed diseases was 49.1±33.8 versus 35.5±37.3 for complete &partial responder, P 0.05.Complete concordance was detected between high serum OSP by ELIZA and OSP gene mutation in 69 tumors (79.3%) while, complete concordance between Normal/Low serum OSP by ELIZA and non-mutant OSP was observed in 28 tumors (60.8%).
OSP is a reliable prognostic biomarker for MBC.Concordance between ELIZA and sequencing techniques denoting that any of these methods may be used for osteopontin assessment. Increased OSP mutation in TNBC may help for tailoring treatment in this very aggressive subtype.
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All authors have declared no conflicts of interest.