EFFECT OF IV GLUCOSE VERSUS COMBINED IV PLUS ORAL GLUCOSE ON HUMAN TUMOR EXTRACELLULAR PH FOR POTENTIAL SENSITIZATION TO THERMORADIOTHERAPY

The purpose of this study was to determine whether intravenous or comb ined intravenous plus oral glucose administration was more effective i nducing acute tumour acidification. Seventeen nondiabetic patients at the Henan Tumour Hospital with superficial tumour deposits of various histologies and size were administered, after fasting, either 50 g glu cose intravenously (I.V., in 100 ml over 10 min) or 50 g I.V. glucose tin 100 ml over 10 min) combined with 100 g oral glucose tin 200 ml, I .V. + oral). Extracellular tumour pH (pH(e)) was determined with one o r two indwelling needle combination pH microelectrodes. Blood glucose concentration was determined every 15-20 min by finger stick with Chem Strips(TM) and Glucometer(TM). Ten patients received I.V. glucose, and seven patients recieved I.V. + oral glucose. Blood glucose rose to 43 0 +/- 15 mg/dL in both groups. However, the rate of clearance of blood glucose was greater for the I.V. glucose than for the I.V. + oral glu cose group (p < 0.00002), and thus the blood glucose levels remained e levated longer after I.V. + oral than after I.V. glucose administratio n. Relative to the initial fasting blood glucose concentration, blood glucose was -2 +/- 7 mg/dL at 110 min after glucose administration by the I.V. route, whereas, blood glucose relative to initial values was 143 + 23 mg/dL by 110 min after glucose administration by the I.V. + o ral route, p = 0.000004. The initial pH, values in the two groups of r umours were similar, 7.34 +/- 0.09 (6.78-7.71) and 7.35 +/- 0.08 (6.99 -7.61), respectively. After I.V. glucose, tumour acidification occurre d in nine of ten patients (-0.16 +/- 0.02 pH unit, range -0.24 to -0.0 5), and after I.V. + oral glucose tumour acidification occurred in six of seven patients (-0.19 + 0.07 pH unit, range -0.43 to -0.06). When the initial fasting blood glucose concentration was in excess of 82 mg /dL, all patients (12/12) exhibited tumour acidification during hyperg lycaemia, whereas, only 3/5 patients exhibited tumour acidification wh en the initial blood glucose concentration was less than 82 mg/dL (p = 0.07). The time to maximum decrease in tumour pH, was significantly s horter after I.V. + oral glucose than after I.V. glucose (e.g., 67 +/- 11 versus 102 +/- 8 min, p = 0.02) and correlated with the rate of cl earance of blood glucose 0,= 0.02, r = 0.55). Larger tumours tended to exhibit a greater decrease in pH, Ca = 0.08, r = 0.04). The only side effects of hyperglycaemia were transient nausea and increased urinary output. The effect of hyperglycaemia induced by administration of 200 g oral glucose was similar to I.V. administration in that 83% of tumo urs exhibited acidification of 0.14 +/- 0.02 pH unit by 91 +/- 7 min. We conclude that I.V. and I.V. + oral glucose administration are equal ly effective inducing tumour acute acidification, but no more effectiv e than 200 g oral glucose, for investigation of hyperglycemic sensitiz ation to thermoradiotherapy.