Serum phosphohexose isomerase in cancer. III.As an index of tumor growth in metastatic carcinoma of the prostate

N 1943 Warburg and Christian28 suggested I that the excessive glycolytic activity of neoplasms might be manifested in vivo by the passage of various glycolytic enzymes into the serum.In working out the implications of this concept, these investigalors and, later, Sibley and Lehninger observed that serum-aldolase activity was increased to some extent in rats bearing transplanted tumors.The latter also reported that the level of serum aldolase was elevated in about 20 per cent of patients with cancer.More recently, Baker and Govan have found that the activity of serum aldolase was high in patients with advanced carcinoma of the prostate and that various therapeutic measures krequently resulted in a reduction of the serum aldolase to a normal range.Little is definitely known about the source of plasma or serum enzymes in the normal organism or about the mechanism of the passage of enzymes from tissue to the circulation in health or disease.Elevations in the level of glycolytic enzymes in the serum in cancer may conceivably be due to one or more of the following: excessive tissue glycolysis, destruction or damage of contiguous normal tissue by the invading or metastatic carcinoma, or factors that cause passage of enzyme from the cell, such as recently described by Warburg and Hiepler29 for aldolase.