Serum phosphoexose isomerase in cancer.

Serum levels of phosphoexose isomerase (PHI) were determined in 138 cancer patients. The enzyme levels showed a relation to the clinical stage of the tumor, and were, on the average, higher in advanced disease. The behavior of the enzyme levels after chemotherapy and/or radiotherapy was studied in relation to the clinical response. A statistically significant reduction of PHI activity in patients with subjective and objective or only subjective responses to therapy was noted. The mean values before and after chemotherapy in patients with progression of the disease were not significantly different. The authors conclude that high levels of serum PHI are, most often, associated with an advanced and/or a metastasized tumor; furthermore PHI seems to be a reliable biologic marker of the destruction of cancer tissue.