@misc{oai:repo.qst.go.jp:00070950,
 author = {Matsumoto, Yoshitaka and Uzawa, Akiko and Hirayama, Ryoichi and Koike, Sachiko and Koda, Kana and Masunaga, Shinichiro and Ando, Koichi and Furusawa, Yoshiya and 松本 孔貴 and 鵜澤 玲子 and 平山 亮一 and 小池 幸子 and 幸田 華奈 and 古澤 佳也},
 month = {Oct},
 note = {[Background and Purpose] The fractionated irradiation is standard protocol for radiotherapy including carbon-ion beam (C-ions) therapy. There are big differences between single and fractionation, for example on DNA damage repair, reoxygenation of hypoxic region, etc. It is necessary to get the results using fractionated
irradiation to know the effects in clinical. The purpose of this study is to examine
the effects of fractionated irradiation for metastasis using C-ions and X-rays.
[Materials and Methods] A mouse osteosarcoma cells, LM8 having highly metastatic potential were used. C-ions irradiation (290 MeV/u) was performed at the center
position of 6cm-SOBP, and X-rays were used as reference beam. The interval among each fraction was 24 hours, and 1 to 5 fractions were used. [in vitro] The cytotoxic
effects were examined using colony formation assay, and the anti-metastatic effects
were examined by the inhibition of migration and invasion activities using Boyden chamber assay and Matrigel invasion assay, respectively. [in vivo] LM8 tumors inoculated into right hind leg of mice were irradiated at 12days after inoculation. Radiosensitivity for individual cell in a tumor was examined by in vivo-in vitro
assay. The metastatic effects were analyzed with the spontaneous lung metastasis
model.
[Results] [in vitro] After X-rays fractionation, cell survival and metastatic
potentials (migration and invasion activities) were increased depend on the fraction number, and the degree was significant at low dose region. On the other hand, the enhancement was not significant after C-ions fractionation. [in vivo] The survival of cells in local tumor and the number of lung metastatic nodules were increased with
the increment of the fraction number after fractionated irradiation. The degree of increase was more remarkable by X-rays than C-ions. The RBE values of C-ions were increased with fraction number on both cell killing and suppression of metastasis,
and the values were larger on metastasis suppression than on cell killing.
[Conclusion] It is confirmed that the anti-metastatic effects showed the dependency
of the fraction number as well as cell killing effects. The degree of the dependency
was more significant for X-rays compared with C-ions with high LETs than X-rays with low LETs. It was suggested that C-ions therapy was superior to photon therapy not
only on tumor cell killing but also on metastasis suppression even for clinical fractionated irradiation., 39th Annual Meeting of the European Radiation Research Society},
 title = {The effect of fractionated carbon-ion beams to tumor metastasis},
 year = {2012}
}