Time course of reoxygenation in experimental murine tumors after carbon-beam and X-ray irradiation.
We compared the tumor reoxygenation patterns in three different murine tumor cell lines after X-irradiation with those after carbon-beam irradiation using a heavy-ion medical accelerator (HIMAC) system. The tumors of the cell lines SCCVII, SCCVII-variant-1 and EMT6 on the hind legs of mice received local priming irradiation with a carbon-beam (8 Gy, 73 keV/microm in LET, 290 MeV/u, 6 cm SOBP) or X-rays (13 Gy, 250 kVp). After various intervals, the mice were given whole-body test irradiation (16 Gy. 250 kVp X-ray) either in air or after they were killed. The hypoxic fractions were estimated as the proportions of the surviving fractions of the tumors in killed mice to those in air-breathing mice. In the SCCVII tumors, the hypoxic fractions at 0.5 h were 50% and 21% (p < 0.05) after the priming X-irradiation and carbon-beam irradiation, respectively. In the SCCVII-variant-1 tumors, the hypoxic fractions were 85% and 82% at 0.5 h, 84% and 20% at 12 h (p < 0.01), and 21% and 31% at 24 h after X-ray and after carbon-beam irradiation, respectively. In the EMT6 tumors, the reoxygenation patterns after X-irradiation and carbon-beam irradiation were quite similar. We concluded that the reoxygenation pattern differed among the three tumor cell lines, and that reoxygenation tended to occur more rapidly after carbon-beam irradiation than after X-irradiation for SCCVII and SCCVII-variant-1 tumors.
Oya
N
N
Department of Therapeutic Radiology and Oncology, Kyoto University Graduate School of Medicine, Shogoin, Japan. oya@kuhp.kyoto-u.ac.jp
Sasai
K
K
Shibata
T
T
Takagi
T
T
Shibuya
K
K
Koike
S
S
Nojima
K
K
Furusawa
Y
Y
Ando
K
K
Hiraoka
M
M
D000818:Animals; D015687:Cell Hypoxia / Q000502:physiology*; D051379:Mice; D009374:Neoplasms, Experimental / Q000532:radiotherapy*; D010100:Oxygen; D014407:Tumor Cells, Cultured
D010100:Oxygen