Scientists at The Institute of Cancer Research, London, demonstrated that a form of magnetic resonance imaging (MRI) can be used to detect and map low levels of oxygen within tumours – as a means of predicting if the disease will respond to radiation treatment.
Tumours with areas of low oxygen concentration – called hypoxia – respond less well to radiation therapy, are more likely to spread, and have a greater chance of returning after being apparently removed. Hypoxic tumours are also more likely to become resistant to some drug treatments.
In the future, the imaging technology could help inform which treatments are offered to patients as part of routine care. Initial studies to use the technology in cancer diagnosis are already underway.
This pre-clinical study, published in The International Journal of Radiation Oncology, Biology, Physics, used a mouse model to look at variations in MRI signal intensity caused by the presence of deoxygenated blood in tumours. The study was part-funded by the Medical Research Council and Cancer Research UK.
The researchers took measurements in two stages: once when mice were breathing normal air, and again whilst breathing carbogen, a mixture of 95 per cent pure oxygen and five per cent carbon dioxide.
The researchers were able to detect tumour regions showing changes in MRI signal intensity consistent with the presence of hypoxia.
The research leaders work at the Cancer Research UK and EPSRC Cancer Imaging Centre, based in the Division of Radiotherapy and Imaging at The Institute of Cancer Research (ICR).
Study leader Dr Simon Robinson, Team Leader in the Division of Radiotherapy and Imaging at the ICR, said:
“We know that lower oxygen concentration in tumours is linked with poorer outcomes for patients. Our study shows the feasibility of using this type of MRI scan to inform on whether a tumour has areas of oxygen shortfall, and which could be used for mapping the extent of hypoxia for radiotherapy planning.”