Mode of tumor invasion in oral squamous cell carcinoma: improved grading based on immunohistochemical examination of extracellular matrices.

Abstract

To predict the nodal involvement of oral squamous cell carcinoma (OSCC) many investigators have studied the histologic features of primary tumors. However, conventional histologic grading still is not sufficient to provide an objective and practical evaluation. In this study we tried to modify one standard type of histologic grading, namely, mode of invasion (MI), on the basis of the extracellular matrix (ECM) staining pattern. One hundred seventeen initial biopsies of primary OSCC were histologically examined, and the MI was graded. The expression of a series of ECMs-laminin, type IV collagen, heparin-sulphate proteoglycan, fibronectin, tenascin, decorin, and vitronectin-was immunohistochemically examined. The ECM staining pattern showed a close association with the MI, and was classified into types I and II. The type I staining pattern was observed in the noninvasive cases (MI grades 1 and 2), while type II was in the highly invasive cases (MI grades 4c and 4d). Because the ECM staining pattern in the moderately invasive cases (MI grade 3) included both types I and II, these cases were subdivided and compared. As a result, the type II cases showed a significantly higher incidence of nodal involvement than did the type I cases. An examination of a series of the ECMs, in addition to the conventional histologic examination, is thus considered to provide more objective and practical data to evaluate the invasive and metastatic potential of OSCC.