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BACKGROUND: A cell surface receptor (50 kd) has been recently identified in malignant cells that recognizes the tumor cell adhesive domain (ie, cysteine-serine-valine-threonine-cysteineglycine [CSVTCG]) of thrombospondin (TSP). This Csvtcg-specific TSP receptor can he considered as a new tumor marker, and its concentration on the cell surface may correlate directly with the capacity of tumor cells to invade and metastasize. MATERIALS AND METHODS: Six patients with primary, stages Ill and IV squamous cell carcinomas of the head and neck were studied. Tumor sections were specifically stained for this receptor with immunohistochemical techniques. The stained specimens were then subjected to computer-assisted image analysis. The area of positive staining and the heterogeneity of the pattern of staining were compared to peritumoral angiogenesis and clinical outcome of the patients. RESULTS: The results indicate that those patients with a high and homogenous positive stain score (mean [+ or -] standard error [SE] 78 [+ or -] 5%) for the Csvtcg-specific TSP receptor had high microvessel density and died from metastatic disease within 12 months of initial treatment (correlation coefficients = 0.95 and 1, respectively). Patients with a low and heterogenous positive stain score for receptor (mean [+ or -] SE 8 [+ or -] 2%; P

Background. Thrombospondin is a high molecular weight glycoprotein, originally described as a secretion product of platelets, that functions as an adhesive protein in cell-cell and cell-substratum interactions. It promotes metastases in the murine model. Plasma thrombospondin has been shown to be elevated in patients with disseminated breast, lung, and gastrointestinal malignancies. Methods. Blood samples were collected by venipuncture into cubes containing ethylenediamine tetraacetic acid as anticoagulant. They were placed on ice immediately and centrifuged under refrigerated conditions. Plasma was removed and frozen until thrombospondin was quantitated by a competitive enzyme-linked immunosorbent assay. Wilcoxon's two-sample rank-sum test was used to evaluate differences between the patient and control groups. Results. The median plasma thrombospondin level was significantly higher in the patient group compared with the control group, and it was directly correlated with stage of disease. There was no correlation between platelet count and thrombospondin level. Conclusions. Tumor-synthesized thrombospondin could explain the elevated levels in the patent group and also the observation of the correlation between the thrombospondin level and tumor burden. Its function as an adhesive protein may allow it to act as the mediator of metastases. thrombospondin may promote or mediate the metastatic process through its function in cell adhesion. Cancer 1994; 73:2853-8.