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Mol Cancer Ther. 2018 Apr;17(4):858-868. doi: 10.1158/1535-7163.MCT-17-0965. Epub 2018 Feb 7.

Characterizing the Potency and Impact of Carbon Ion Therapy in a Primary Mouse Model of Soft Tissue Sarcoma.

Author information

1
Department of Radiation Oncology, Duke University Health System, Durham, North Carolina.
2
Department of Pharmacology & Cancer Biology, Duke University, Durham, North Carolina.
3
Department of Biology, Brookhaven National Laboratory, Upton, New York.
4
Trento Institute for Fundamental Physics and Applications, National Institute for Nuclear Physics (INFN), Trento, Italy.
5
Department of Physics, University of Trento, Trento, Italy.
6
Brookhaven National Laboratory, Upton, New York.
7
Department of Biostatistics and Informatics, Duke University, Durham, North Carolina.
8
Department of Radiation Oncology, Duke University Health System, Durham, North Carolina. david.kirsch@duke.edu.

Abstract

Carbon ion therapy (CIT) offers several potential advantages for treating cancers compared with X-ray and proton radiotherapy, including increased biological efficacy and more conformal dosimetry. However, CIT potency has not been characterized in primary tumor animal models. Here, we calculate the relative biological effectiveness (RBE) of carbon ions compared with X-rays in an autochthonous mouse model of soft tissue sarcoma. We used Cre/loxP technology to generate primary sarcomas in KrasLSL-G12D/+; p53fl/fl mice. Primary tumors were irradiated with a single fraction of carbon ions (10 Gy), X-rays (20 Gy, 25 Gy, or 30 Gy), or observed as controls. The RBE was calculated by determining the dose of X-rays that resulted in similar time to posttreatment tumor volume quintupling and exponential growth rate as 10 Gy carbon ions. The median tumor volume quintupling time and exponential growth rate of sarcomas treated with 10 Gy carbon ions and 30 Gy X-rays were similar: 27.3 and 28.1 days and 0.060 and 0.059 mm3/day, respectively. Tumors treated with lower doses of X-rays had faster regrowth. Thus, the RBE of carbon ions in this primary tumor model is 3. When isoeffective treatments of carbon ions and X-rays were compared, we observed significant differences in tumor growth kinetics, proliferative indices, and immune infiltrates. We found that carbon ions were three times as potent as X-rays in this aggressive tumor model and identified unanticipated differences in radiation response that may have clinical implications. Mol Cancer Ther; 17(4); 858-68. ©2018 AACR.

PMID:
29437879
PMCID:
PMC5912881
[Available on 2019-04-01]
DOI:
10.1158/1535-7163.MCT-17-0965

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