@misc{oai:repo.qst.go.jp:00070162,
 author = {Matsumoto, Yoshitaka and Koike, Sachiko and Uzawa, Akiko and Hirayama, Ryoichi and Okayasu, Ryuichi and Ando, Koichi and Furusawa, Yoshiya and et.al and 松本 孔貴 and 小池 幸子 and 鵜澤 玲子 and 平山 亮一 and 岡安 隆一 and 古澤 佳也},
 month = {May},
 note = {Purpose: Up to 2009, over 5000 patients have been treated in HIMAC. Malignant melanoma showed high local control of about 75%, whereas the overall survival was about 36% at 5-years. It is an important subject to control tumor distant metastasis for heavy-ion radiotherapy. The aim of this study is to clarify the effect of carbon ion beams (C-ion) on metastatic potential of melanoma in vitro and in vivo. 
Materials and Methods:  A highly metastatic mouse malignant melanoma cell line B16/BL6 were maintained in RPMI-1640 medium supplemented with 10% FBS and antibiotics. [in vitro] Samples were prepared 2 days before and then irradiated with C-ions at 13, 50 or 75 keV/um or X-rays. Surviving fractions were obtained using colony formation assay. Migration and invasion activity as metastatic potentials of the cells were examined using the Boyden-chamber method and the Matrigel invasion assay. [in vivo] The cells were implanted in right-leg of C57BL/6J mice at 1x106 cells/mouse 9-10 days before irradiation. Tumors were irradiated at the center of 6cm-SOBP of C-ions, or gamma-rays. Radiosensitivity for whole tumor was obtained by the tumor growth delay method, and that for individual cell in a tumor was obtained by an in vivo-in vitro assay. The metastatic effects were analyzed with the spontaneous lung metastasis model. 
Results: [in vitro] Survival curves showed higher cytotoxic effects of C-ions compared with X-rays, and the RBE values were 1.1, 1.7 or 2.5 at 13, 50, or 75 keV/um, respectively. The potential of migration and invasion were suppressed by C-ions at all dose points (0.25 to 8.0 Gy) tested, however it was enhanced by X-rays at low dose points (0.25 to 0.5Gy) than non-irradiated controls. The RBE values obtained from migration and invasion test were higher than that from cell killing.  [in vivo] C-ions significantly suppressed the tumor growth, and the RBE was 2.6.  The numbers of lung metastatic nodules after tumor-irradiations decreased with the dose, and C-ions were more effective compared with gamma-rays.  The metastatic potentials of survived cells in a tumor after irradiation was analyzed with the number of metastatic lung colony from implanted tumors and survival of irradiated and explanted cells from a tumor.  
Smaller number of metastasis was found for C-ions than gamma-rays when the tumor cell survivals were 10%.  
Conclusion:  It might suggest that C-ion inhibit metastasis at radiotherapy compared with low-LET photons., PTCOG 49},
 title = {The effects of heavy-ion and photon beams to mouse malignant melanoma cell line having highly metastatic potential},
 year = {2010}
}