Expression of c-Met, a gene for the hepatocyte growth factor/scatter factor (HGF/SF) receptor, is known to be associated with tumour development in several human carcinomas. The expression of c-Met was examined using immunohistochemistry in 82 cases of primary laryngeal carcinoma to evaluate the tissue distribution of c-Met and the clinicopathological significance of c-Met expression. In normal larynx, c-Met expression was observed only in some minor salivary glands. Positive reaction for c-Met in neoplastic epithelium was noted in 45 out of 82 (54.9%) cases. In 44 cases, structures adjacent to the carcinoma (noncancerous squamous epithelium, some stromal fibroblastic cells, and endothelial cells) showed positive reaction for c-Met. c-Met expression in cancerous epithelium was significantly correlated with lymph node status (P<0.04) and proliferating activity expressed by the Ki-67 labelling index (P<0.02). There was no correlation between c-Met expression and age, sex, histological type, T category, distant metastasis or clinical stage. The data suggest that overexpression of c-Met in laryngeal carcinomas represents a growth advantage for cancer cells, which may be conferred by the mitogenic effect of HGF/SF. Simultaneous c-Met expression in noncancerous components of the larynx may represent a paracrine modification of c-Met.
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