METABOLISM OF NEOPLASTIC TISSUE. XVII. BLOOD GLUCOSE REPLACEMENT RATES IN HUMAN CANCER PATIENTS.

Abstract

Summary Kinetic methods of measuring rates of glucose turnover, utilizing C 14 -labeled glucose, were applied to human subjects bearing a variety of neoplasms. By measuring rates of decline of the blood glucose specific activity after a single injection of uniformly labeled glucose-C 14 , net turnover rates were estimated. In seventeen patients with cancer the average value of 131 ± 29 mg/kg body weight/hr was not significantly different from the average value of 120 ± 17 mg/kg/hr observed for ten cancer-free subjects. Since this procedure gives only net glucose turnover, uncorrected for glucose resynthesized from labeled 3-carbon metabolites via the Cori cycle, a new procedure was applied, based on the randomization of labeling which occurs when glucose-1-C 14 is broken down to 3-carbon fragments and is resynthesized to glucose. In seven subjects with cancer “corrected” turnover rates ranged from 124 to 370 mg/kg/hr, with an average of 192/kg/hr, as compared with an average of 161 mg/kg/hr for four normal subjects. Average recycling rates were 50 ± 20 mg/kg/hr for the cancerous subjects and 26 ± 6 mg/kg/hr for the normals. The data indicate that rates of replacement and recycling of blood glucose may be higher in subjects with cancer, but the differences were not as marked as one would have expected in view of the generally high glycolytic activity of tumors in vitro .