C1 esterase inhibitor protein associated with human cancer: a tumour marker

The concentration of a cancer-associated serum C1 esterase inhibitor protein was determined in 194 cases of human cancer, grouped according to their clinical activity. As control groups healthy blood donors and patients having non neoplastic chronic lung and liver diseases were included in the study. The results showed highly significant differences when the values obtained for "active" malignant tumors were compared with the two control groups and the quiescent tumours. The authors conclude that C1 esterase inhibitor protein measurement may be useful as a clinical tumour marker.