Stromal fibronectin staining pattern and metastasizing ability of human breast carcinoma

The peripheral stromal fibronectin (FN) staining patterns of invasive breast carcinomas (IBC) from 77 women were compared to the aggressivity of the tumors, which in each case had been determined through a complete clinical follow-up and autopsy investigation. Polyclonal, monospecific rabbit antibody to human FN was applied on formalin-fixed, paraffin-embedded tissue sections using the peroxidase-antiperoxidase staining technique. An FN-positive staining reaction was defined as a constant, diffuse, or pericellular demarcation of FN-positive fibers surrounding tumor cells at the invasive border. In lack of such a staining pattern, FN-negative staining was recorded. The FN-positive staining reaction was significantly associated with a low metastatic potential and appeared in a multivarians analysis to be an excellent prognostic factor, which surpassed other known parameters, such as clinical stage, histological type or grade, and lymph node status. 27 out of 31 women, who died without evidence of metastatic spread, had FN-positive IBC (87%) in contrast to women with metastatic disease, where only 15 out of 46 had FN-positive tumors (33%). An extensive histopathological examination of the contralateral breast revealed in this latter group a high rate of second primaries (22/46), which might have been responsible for the metastatic spread. If these women with bilateral IBC were excluded, only three metastasizing tumors with a FN-positive staining pattern remained, suggesting that the prognostic value of the FN-staining pattern along the invasive border of IBC might be even higher than anticipated from this study.