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Genetic Test Predicts Colon Tumor Sensitivity to Radiation Therapy

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Key Points

  • Metastatic colon tumors are more resistant to radiation than primary colon tumors; radiation sensitivity may also be dependent on the anatomic location of the tumor metastasis.
  • Patients with lung metastasis had a better response to radiation than patients with liver metastasis, as predicted by radiation sensitivity index.
  • Researchers estimate that up to 15% of patients will be candidates for dose optimization. 

Recent advances in the understanding of cancer have led to the development of more personalized therapies. Moffitt Cancer Center researchers have contributed to these advances by developing the first test that analyzes the sensitivity of tumors to radiation therapy. Their findings were published by Ahmed et al in the International Journal of Radiation OncologyBiology Physics. 

Researchers from Moffitt previously developed a radiation sensitivity index that predicts how sensitive tumors are to radiation based on expression patterns of different genes. They used the radiation sensitivity index to determine the radiation sensitivity of 704 metastatic and 1,362 primary colon tumors.

Study Findings

The investigators discovered that metastatic colon tumors are more resistant to radiation than primary colon tumors. They also reported that radiation sensitivity may be dependent on the anatomic location of the tumor metastasis.

The researchers confirmed some of these findings by analyzing how effective radiation therapy was in 29 colon cancer tumors that metastasized to either the liver or lung. Their findings validated that patients with metastatic disease in their lungs had a better response to radiation then those who had metastatic disease in their liver, as predicted by the radiation sensitivity index.

These results highlight the importance of the location of the metastasis, as well as the location of the original primary tumor, in predicting response to radiation therapy. They suggest that it may be possible to personalize radiation therapy for patients.

“Radiation sensitivity index provides the first opportunity to use tumor genetics to guide and optimize the radiation dose that patients receive. The consequences for this can be quite dramatic. We have estimated that up to 15% of patients will be candidates for dose optimization,” explained Javier F. Torres-Roca, MD, Director of Clinical Research and Associate Member of the Department of Radiation Oncology at Moffitt.

According to editors of the International Journal of Radiation OncologyBiologyPhysics, “Radiation sensitivity index is important progress towards personalizing radiation therapy. The results generate important hypotheses that could dramatically influence patient care.”

Dr. Torres-Roca is the corresponding author for the International Journal of Radiation OncologyBiologyPhysics article.

The research was supported by grants and awards received from the National Institutes of Health, the US Army Medical Research and Materiel Command, the National Functional Genomics Center, the Bankhead-Coley Foundation, and the DeBartolo Family Personalized Medicine Institute.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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