PROCOAGULANT ACTIVITY MAY BE A MARKER OF THE MALIGNANT PHENOTYPE IN EXPERIMENTAL PROSTATE-CANCER

Using a one-stage kinetic chromogenic assay, we studied the procoagulant activity (PCA) of prostatic tissue in an experimental model of prostate cancer in the rat. PCA was present in homogenates of rat prostate glands containing either benign or malignant tumours. The procoagulant activated factor X directly and was provisionally characterised as a tissue factor-factor VIIa complex. There was no significant differences in PCA between control rats and rats exposed to carcinogens that did not develop tumour. Levels in rats that developed tumours were significantly higher (P<0.01) than all other groups and there was a positive correlation between tumour weight and PCA (r = 0.85, P<0.001). Furthermore, prostatic PCA levels were higher (P<0.01) in those tumours that had spread than in those which were organ confined. In five animals, the PCA of the primary tumour was compared with that of the corresponding secondary deposit and levels were higher in the metastasis (P<0.02). We conclude that PCA reflects the malignant phenotype in this model of experimental prostate cancer and suggest that this parameter is worth evaluating as a potential tumour marker in the human disease.