Fibronectin concentration in the plasma of patients with malignant and benign breast disease.

Fibronectin concentration was determined in plasma from 97 patients with benign or malignant breast disease and from 62 controls. Median plasma fibronectin concentration (microgram FN/ml plasma) appeared to be significantly higher in patients with non-metastatic or metastatic breast cancer as compared to age-matched controls (P less than 0.01 and P less than 0.03, respectively); however, statistical significance disappeared when results were expressed as a function of total plasma protein content (microgram FN/mg total plasma protein). In patients with benign breast disease plasma fibronectin values were not significantly different from control levels. Our data indicate that the clinical usefulness of measuring FN in breast cancer patients appears to be very limited.