Expression of matrix metalloproteinase-9 in high-grade salivary gland carcinomas is associated with their metastatic potential

OBJECTIVE: The aim of this study was to investigate the role of matrix metalloproteinase (MMP)-9 protein in high-grade malignant tumors of salivary gland origin as well as its utility as a prognostic marker. METHODS: Four micrometer sections from 27 malignant salivary neoplasms were immunostained using a specific antibody against MMP-9. The staining results (proportion of the stained tumor cells and intensity of tumor stainings) were correlated with the clinical data and with patient outcomes. RESULTS: Immunostaining for MMP-9 was observed in 17 cases, predominantly localized in the tumor cells and occasionally in the inflammatory stroma cells. MMP-9 protein expression correlated with N (P = .04), M (P = .02), and TNM stages (P = .03). MMP-9 expression was prognostic for shortened survival (P = .01). Our results show that the invasiveness and prognosis of high-grade salivary gland cancers may depend on their MMP-9 expression profile.