Lee Moffitt Cancer Center (FL, USA) researchers have utilized a radiation sensitivity index to identify varying radiosensitivities of colon cancer metastases based on their location within the body. This is one of the first research studies to highlight the importance of the location of metastases as well as the location of the original primary tumor in predicting response to radiation therapy.
The radiation sensitivity of 704 metastatic and 1362 primary colon tumors was determined using a radiation sensitivity index previously discovered by the team, which predicts sensitivity based on gene expression patterns. When compared, metastatic colon tumors demonstrated more resistance to radiation therapy than primary tumors of the colon. The team also reported that tumor metastases in different anatomic locations had varying levels of sensitivity, signifying that radiation sensitivity could be dependent on tumor location.
The results were validated by analyzing the effectiveness of radiation therapy in 29 colon cancer tumors that had metastasized to either the liver or lung. As predicted by the radiation sensitivity index, patients with lung metastases had a better response and increased sensitivity to radiation therapy than patients with liver metastases.
Javier F Torres-Roca, senior author and Director of Clinical Research at Lee Moffit commented: “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.”
Radiation sensitivity indexes could prove to be an important tool in influencing patient care in the future. The study results suggest that it may be possible to develop targeted tests to predict patient response to therapy as well as personalizing radiation therapy overall.