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Comparison of human chordoma cell-kill for 290 MeV/n carbon ions versus 70 MeV protons in vitro.

Fujisawa H, Genik PC, Kitamura H, Fujimori A, Uesaka M, Kato TA - Radiat Oncol (2013)

Bottom Line: This is the first report and characterization of a direct comparison between the effects of charged particle carbon ions versus protons for a chordoma cell line in vitro.Our results support a potentially superior therapeutic value of carbon particle irradiation in chordoma patients.Carbon ion therapy may have an advantage for chordoma radiotherapy because of higher cell-killing effect with high LET doses from biological observation in this study.

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ABSTRACT

Background: While the pace of commissioning of new charged particle radiation therapy facilities is accelerating worldwide, biological data pertaining to chordomas, theoretically and clinically optimally suited targets for particle radiotherapy, are still lacking. In spite of the numerous clinical reports of successful treatment of these malignancies with this modality, the characterization of this malignancy remains hampered by its characteristic slow cell growth, particularly in vitro.

Methods: Cellular lethality of U-CH1-N cells in response to different qualities of radiation was compared with immediate plating after radiation or as previously reported using the multilayered OptiCell™ system. The OptiCell™ system was used to evaluate cellular lethality over a broad dose-depth deposition range of particle radiation to anatomically mimic the clinical setting. Cells were irradiated with either 290 MeV/n accelerated carbon ions or 70 MeV accelerated protons and photons and evaluated through colony formation assays at a single position or at each depth, depending on the system.

Results: There was a cell killing of approximately 20-40% for all radiation qualities in the OptiCell™ system in which chordoma cells are herein described as more radiation sensitive than regular colony formation assay. The relative biological effectiveness values were, however, similar in both in vitro systems for any given radiation quality. Relative biological effectiveness values of proton was 0.89, of 13-20 keV/μm carbon ions was 0.85, of 20-30 keV/μm carbon ions was 1.27, and >30 keV/μm carbon ions was 1.69. Carbon-ions killed cells depending on both the dose and the LET, while protons depended on the dose alone in the condition of our study. This is the first report and characterization of a direct comparison between the effects of charged particle carbon ions versus protons for a chordoma cell line in vitro. Our results support a potentially superior therapeutic value of carbon particle irradiation in chordoma patients.

Conclusion: Carbon ion therapy may have an advantage for chordoma radiotherapy because of higher cell-killing effect with high LET doses from biological observation in this study.

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Related in: MedlinePlus

Cell survival curves at each depth in water. Cell survival assays were conducted with stacked OptiCell™ cell culture systems, irradiated with 290 MeV/n carbon ions: A-C and 70 MeV protons: D-F. Error bars indicate standard errors of the means from as many as four independent experiments.
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Figure 2: Cell survival curves at each depth in water. Cell survival assays were conducted with stacked OptiCell™ cell culture systems, irradiated with 290 MeV/n carbon ions: A-C and 70 MeV protons: D-F. Error bars indicate standard errors of the means from as many as four independent experiments.

Mentions: Cell survival assays were conducted with our stacked OptiCell™ cell culture system, and cells irradiated with carbon ion and proton particles. Positions of OptiCell™ chambers at each depth were altered to the depths in water using the physical parameters determined in our previous report [21]. Bragg peaks of each carbon and proton beams were delivered at depths of 14 and 4 cm, respectively (Figure 1). Survival fractions were gradually decreased and minimized at the Bragg peaks. Survival fraction near the Bragg peaks for carbon showed lower survival fractions compared to those for protons (Figure 2A-F).


Comparison of human chordoma cell-kill for 290 MeV/n carbon ions versus 70 MeV protons in vitro.

Fujisawa H, Genik PC, Kitamura H, Fujimori A, Uesaka M, Kato TA - Radiat Oncol (2013)

Cell survival curves at each depth in water. Cell survival assays were conducted with stacked OptiCell™ cell culture systems, irradiated with 290 MeV/n carbon ions: A-C and 70 MeV protons: D-F. Error bars indicate standard errors of the means from as many as four independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3643831&req=5

Figure 2: Cell survival curves at each depth in water. Cell survival assays were conducted with stacked OptiCell™ cell culture systems, irradiated with 290 MeV/n carbon ions: A-C and 70 MeV protons: D-F. Error bars indicate standard errors of the means from as many as four independent experiments.
Mentions: Cell survival assays were conducted with our stacked OptiCell™ cell culture system, and cells irradiated with carbon ion and proton particles. Positions of OptiCell™ chambers at each depth were altered to the depths in water using the physical parameters determined in our previous report [21]. Bragg peaks of each carbon and proton beams were delivered at depths of 14 and 4 cm, respectively (Figure 1). Survival fractions were gradually decreased and minimized at the Bragg peaks. Survival fraction near the Bragg peaks for carbon showed lower survival fractions compared to those for protons (Figure 2A-F).

Bottom Line: This is the first report and characterization of a direct comparison between the effects of charged particle carbon ions versus protons for a chordoma cell line in vitro.Our results support a potentially superior therapeutic value of carbon particle irradiation in chordoma patients.Carbon ion therapy may have an advantage for chordoma radiotherapy because of higher cell-killing effect with high LET doses from biological observation in this study.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: While the pace of commissioning of new charged particle radiation therapy facilities is accelerating worldwide, biological data pertaining to chordomas, theoretically and clinically optimally suited targets for particle radiotherapy, are still lacking. In spite of the numerous clinical reports of successful treatment of these malignancies with this modality, the characterization of this malignancy remains hampered by its characteristic slow cell growth, particularly in vitro.

Methods: Cellular lethality of U-CH1-N cells in response to different qualities of radiation was compared with immediate plating after radiation or as previously reported using the multilayered OptiCell™ system. The OptiCell™ system was used to evaluate cellular lethality over a broad dose-depth deposition range of particle radiation to anatomically mimic the clinical setting. Cells were irradiated with either 290 MeV/n accelerated carbon ions or 70 MeV accelerated protons and photons and evaluated through colony formation assays at a single position or at each depth, depending on the system.

Results: There was a cell killing of approximately 20-40% for all radiation qualities in the OptiCell™ system in which chordoma cells are herein described as more radiation sensitive than regular colony formation assay. The relative biological effectiveness values were, however, similar in both in vitro systems for any given radiation quality. Relative biological effectiveness values of proton was 0.89, of 13-20 keV/μm carbon ions was 0.85, of 20-30 keV/μm carbon ions was 1.27, and >30 keV/μm carbon ions was 1.69. Carbon-ions killed cells depending on both the dose and the LET, while protons depended on the dose alone in the condition of our study. This is the first report and characterization of a direct comparison between the effects of charged particle carbon ions versus protons for a chordoma cell line in vitro. Our results support a potentially superior therapeutic value of carbon particle irradiation in chordoma patients.

Conclusion: Carbon ion therapy may have an advantage for chordoma radiotherapy because of higher cell-killing effect with high LET doses from biological observation in this study.

Show MeSH
Related in: MedlinePlus