Response of intracerebral human glioblastoma xenografts to multifraction radiation exposures.
OBJECTIVE
We investigated the effects of fractionated radiation treatments on the life spans of athymic rats bearing intracerebral brain tumors.


METHODS
U-251 MG or U-87 MG human glioblastoma cells were implanted into the brains of athymic rats, and the resulting tumors were irradiated once daily with various doses of ionizing radiation for 5 consecutive days or for 10 days with a 2-day break after Day 5.


RESULTS
Five daily doses of 1 and 1.5 Gy, and 10 doses of 0.75 and 1 Gy, cured some U-251 MG tumors. However, five daily doses of 0.5 Gy increased the survival time of animals bearing U-251 MG tumors 5 days without curing any animals of their tumors. Ten doses of 0.3 Gy given over 2 weeks extended the lifespan of the host animals 9 days without curing any animals. For U-87 MG tumors, 5 daily doses of 3 Gy produced an increased lifespan of 8 days without curing any animals, and 10 doses of 1 Gy prolonged lifespan 5.5 days without curing any animals. The differences in extension of life span between the 5- and 10-fraction protocols were minor for either tumor type.


CONCLUSIONS
The finding that the U-251 MG tumors are more sensitive than U-87 MG tumors, despite the fact that U-251 MG tumors contain many more hypoxic cells than U-87 MG tumors, suggests the intrinsic cellular radiosensitivities of these cell lines are more important than hypoxia in determining their in vivo radiosensitivities.
Ozawa
Tomoko
T
Brain Tumor Research Center, Department of Neurological Surgery, University of California San Francisco, San Francisco, CA 94143, USA.
Faddegon
Bruce A
BA
Hu
Lily J
LJ
Bollen
Andrew W
AW
Lamborn
Kathleen R
KR
Deen
Dennis F
DF
D000818:Animals; D001932:Brain Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D019583:Dose Fractionation, Radiation; D005909:Glioblastoma / Q000401:mortality / Q000532:radiotherapy*; D006801:Humans; D008017:Life Expectancy; D008297:Male; D011836:Radiation Tolerance / Q000502:physiology; D051381:Rats; D011923:Rats, Nude; D014183:Transplantation, Heterologous