Oncofetal fibronectin and oral squamous cell carcinoma.

Fibronectin is a cell matrix glycoprotein, which exists as a number of isoforms that are often found within the cell matrix that surrounds tumours. Collectively these tumour-associated isomers of fibronectin have been termed oncofetal fibronectin (OFFN). We looked for expression of OFFN within oral squamous cell carcinomas (SCC) and related its presence to prognosis. The investigation used a monoclonal antibody (MoAb 5C10) to the glycosylated variant of OFFN, and 100 archival specimens of oral SSC. Immunostaining for OFFN was intense in the adjacent stroma of 43 squamous carcinomas, weak in 27 and absent in 30. Cervical metastases were found in 17/27 (63%) specimens that stained intensely, 6/17 (35%) that stained weakly and 3/13 (23%) that did not stain. Of the 21 cases which had extracapsular lymph node spread, 81% were from those that stained intensely, 19% from those that stained weakly and none from those that did not stain for OFFN expression. Also, 21/44 patients (49%) died in group with intense OFFN staining, 6/26 (23%) in the group with weak staining and 3/30 (10%) in the group that did not stain. The presence of OFFN glycoprotein in oral SCC as evaluated by immunostaining with MoAb 5C10 correlates strongly with the presence of metastatic lymph node involvement, particularly extracapsular involvement, and mortality. We therefore suggest that the degree of expression of OFFN in tumours is a valuable prognostic indicator.