Tissue factor assays as diagnostic tools for cancer? Correlation between urinary and monocyte tissue factor activity

Monocyte and urinary tissue factors (mTF and uTF) are both elevated in a number of pathologic conditions, including cancer. This study validates the best available uTF and mTF assays as diagnostic tools for cancer and examines if uTF levels reflect monocyte activation. Using kinetic chromogenic assays for uTF and mTF (measured on fresh resting cells [baseline], unstimulated cells, and lipopolysaccharide [LPS]-stimulated cells), we assessed TF levels in normal individuals, surgical controls, and patients with benign and malignant diseases. Each benign disease group was stratified as inflammatory or noninflammatory. Controls and benign noninflammatory results were indistinguishable. The malignant and inflammatory groups showed raised uTF levels over controls (p < 0.001). mTF levels differ similarly. For mTF and uTF assays, there was no significant difference between the malignant and inflammatory groups. The relative operating characteristic (ROC) curve plots sensitivity against false positive rate (1-specificity) for all possible cutoff values of a diagnostic test. Assay performance is assessed as the area under the curve (AUC). The ROC curve for the uTF assay displayed both sensitivity and specificity for cancer, the AUC being 0.83. Of the three mTF levels, LPS-stimulated cells gave the optimum curve (AUC = 0.71). uTF showed a weak to moderate association with mTF levels but correlated best and was statistically significant when compared with levels in the LPS-stimulated cells. uTF represents an intrinsic, kidney-derived, physiologic concentration rather than that of preactivated or postactivated monocytes. In conclusion, both uTF and LPS-stimulated mTF levels showed sensitivity and specificity in detecting cancer and inflammatory diseases. However, the two forms of TF appear to be independently derived.