Cellular fibronectin in serum and plasma: a potential new tumour marker?

The concentration of cellular fibronectin (cFN) containing the extra domain A (EDA) was measured in 479 plasma and 300 serum samples from healthy blood donors by a competitive enzyme immunoassay (EIA). Serum and plasma samples contained low concentrations of EDAcFN. The mean concentration of EDAcFN was higher in plasma (2.46 mg l-1) than in serum (0.30 mg l-1). No significant differences between sexes or age groups were found. The EDAcFN concentrations were also measured in 120 patients with various malignancies. The mean values in serum were 4.28 mg l-1, 2.01 mg l-1 and 5.18 mg l-1 in patients with digestive tract malignancies, breast cancer and a group of miscellaneous cancers respectively. In plasma, the corresponding values were 12.26 mg l-1, 4.38 mg l-1 and 11.12 mg l-1 respectively. The serum EDAcFN concentration was higher than the 97.5th percentile level of healthy blood donors in 86% of patients with digestive tract and in 76% with miscellaneous malignancies. In patients with breast cancer 60% had elevated levels of EDAcFN. The corresponding figures for plasma samples in patients with digestive tract and miscellaneous malignancies were 79% and 71% respectively. In patients with breast cancer only 30% had elevated plasma levels of EDAcFN. The mean values in serum and plasma of 20 patients with benign diseases were below the cut-off levels. Consistent with the EIA results, Western blotting revealed increased amounts of EDAcFN in blood samples from cancer patients. Pregnancy did not affect the EDAcFN concentration. The mean values in 20 pregnant women were below the cut-off levels.