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Significance of tumor heterogeneity in determining biological effectiveness of low and high LET radiation
https://repo.qst.go.jp/records/69072
https://repo.qst.go.jp/records/69072ca56890f-6293-4473-870d-1847c73f71ef
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2007-08-09 | |||||
| タイトル | ||||||
| タイトル | Significance of tumor heterogeneity in determining biological effectiveness of low and high LET radiation | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_c94f | |||||
| 資源タイプ | conference object | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Ando, Koichi
× Ando, Koichi× Koike, Sachiko× Uzawa, Akiko× Furusawa, Yoshiya× Hirayama, Ryoichi× Matsumoto, Yoshitaka× Watanabe, Masahiko× 安藤 興一× 小池 幸子× 鵜澤 玲子× 古澤 佳也× 平山 亮一× 松本 孔貴× 渡邉 雅彦 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | (Introduction) A dose escalation study of non-small cell lung carcinoma in patients has shown that shape of dose-tumor control probability of carbon-ion radiotherapy is steeper than that of photon therapy, and that relative biological effectiveness (RBE) of carbon ions is larger at higher doses than at lower doses. This contradicts with the biological knowledge; RBE decreases with an increase of dose. A possible explanation is that tumors could contain heterogeneous sub-populations with different photon sensitivities. (Purpose) The purpose of present study is to clarify experimentally significance of tumor heterogeneity. (Materials and Methods) Two sarcomas of # 6107 and #9037 were transplanted into syngeneic C3H male mice. Single cell suspensions for each tumor were mixed together at various ratios just prior to transplantation. When tumors grew to reach 7 mm in diameter, leg tumors were locally irradiated with 290 MeV/n carbon ions at an LET of 74 keV/m that were accelerated by HIMAC synchrotron in our institute. Tumor growth (TG) time was obtained by calculating days required for a tumor to reach 5 times initial volume. Both Tumor Growth Delay (TGD) time and Specific Tumor Growth Delay was used to obtain isoeffect doses. RBE values were calculated by comparing isoeffect doses between carbon ions and reference Cs-137 gamma rays. (Results and Discussion) TG time of unirradiated control was similar between #6107 and #9073, i.e., 5.6 and 6.1 days. Tumors with different ratios of mixture (RM) showed various TG time such that TG times of 8.3, 3.8 and 6.1 days were for tumors with ratios of 9:1, 5:5 and 1:9 (#6107: #9037), respectively. Isoeffect doses for 5 tumors with different RM were ranging from 18 to 48 Gy for gamma rays, and from 8 to 18 Gy for carbon ions. A tumor with RM of 9:1 showed largest isoeffect dose, and was more resistant than the either parental tumors of #6107 or #9037 tumors. RBE of the tumor with RM of 9:1 was largest, and larger than that of the parental tumors with RM of 10:0 and 0:10. This means any interaction between sub-populations could modify radiosensitivity of a tumor. Possible reasons for this interaction are either hypoxic ell fraction or G1 cell cycle phase. Factor(s) and/or signals responsible to the interaction are unknown. (Conclusion) Tumor heterogeneity is a significant determinant for tumor radiosensitivity and RBE of high LET radiation. | |||||
| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 13th International Congres of Radiation Research | |||||
| 発表年月日 | ||||||
| 日付 | 2007-07-12 | |||||
| 日付タイプ | Issued | |||||
