821 Glucose utilization and in vivo cell kinetics in rectal cancer, before and after preoperative radiotherapy

Abstract

Patients with T3/T4 rectal cancers were injected i. v. with 400–555 MBq F–18 FDG. Dynamic imaging was immediately started. Maximum tumor glucose utilization was calculated. Cell kinetics were measured by flow cytometry 6–8 hrs after i. v. injection of IUdR. Two groups of patients were studied: 1) surgery only (n = 8); and 2) preoperative radiotherapy (30 Gy/10 fractions) followed by surgery (RT, n = 6). At baseline, TuGluc for group I was 280 ± 141 (SD) nmo1/min/ml, and for group 2:269 ± 161 (P = NS). After RT, TuGluc decreased to 109 ± 61 (P > 0.05). T pot was 3.50 ± 1.21 days for group I and 3.23 ± 2.23 days for group 2 before RT (P = NS). A negative correlation was found between TuGluc and Tpot, suggesting increasing glucose utilization for faster dividing cells. After RT, Tpot did not change significantly (4.88 ± 3.80 days), whereas TuGluc fell significantly. In conclusion these results show a direct correlation between tumor cell metabolism and tumor cell proliferation in vivo. RT results in a decrease in TuGluc utilization indicating cell loss due to RT, because the proliferating cells don’t proliferate more slowly, and so should not have a smaller TuGluc. Patients with T3/T4 rectal cancers were injected i. v. with 400–555 MBq F–18 FDG. Dynamic imaging was immediately started. Maximum tumor glucose utilization was calculated. Cell kinetics were measured by flow cytometry 6–8 hrs after i. v. injection of IUdR. Two groups of patients were studied: 1) surgery only (n = 8); and 2) preoperative radiotherapy (30 Gy/10 fractions) followed by surgery (RT, n = 6). At baseline, TuGluc for group I was 280 ± 141 (SD) nmo1/min/ml, and for group 2:269 ± 161 (P = NS). After RT, TuGluc decreased to 109 ± 61 (P > 0.05). T pot was 3.50 ± 1.21 days for group I and 3.23 ± 2.23 days for group 2 before RT (P = NS). A negative correlation was found between TuGluc and Tpot, suggesting increasing glucose utilization for faster dividing cells. After RT, Tpot did not change significantly (4.88 ± 3.80 days), whereas TuGluc fell significantly. these results show a direct correlation between tumor cell metabolism and tumor cell proliferation in vivo. RT results in a decrease in TuGluc utilization indicating cell loss due to RT, because the proliferating cells don’t proliferate more slowly, and so should not have a smaller TuGluc.