Scientists at the Wellcome Sanger Institute and the University of Cambridge studied the effects of low doses of radiation equivalent to three CT scans in the esophagus of mice. What they found was that cells capable of becoming cancerous are given a competitive advantage over normal cells in healthy tissues.
Specifically, it increased the number of cells with mutations in p53, a genetic change associated with cancer. However, when they gave the mice an antioxidant before radiation it promoted the growth of healthy cells which outcompeted and replaced the p53 mutant cells. The study has been published in the journal Cell Stem Cell.
The researchers recommend that this risk should be considered when assessing radiation safety. Furthermore, they present the potential of creating non-toxic preventative measures which would cut the risk of developing cancer by helping our healthy cells to eradicate cancer-capable ones as the antioxidant did for the mice.
Dr. David Fernandez-Antoran, the first author from the Wellcome Sanger Institute, said:
Our bodies are the set of ‘Game of Clones’ – a continuous battle for space between normal and mutant cells. We show that even low doses of radiation, similar to three CT scans’ worth, can weigh the odds in favour of cancer-capable mutant cells. We’ve uncovered an additional potential cancer risk as a result of radiation that needs to be recognised.
Exposure for medical imaging (which is a low dose of radiation) is considered safe since it causes little DNA damage and apparently minimal effect on long-term health. Effects like the one they have discovered through this study have never been found before. That is why assessing the associated risk has been difficult.
Professor Phil Jones, the lead author from the Wellcome Sanger Institute and MRC Cancer Unit, University of Cambridge, said:
Medical imaging procedures using radiation, such as CT scans and x-rays, have a very low level of risk – so low that it’s hard to measure. This research is helping us understand more about the effects of low doses of radiation and the risks it may carry. More research is needed to understand the effects in people.
Dr. Kasumi Murai, an author from the Wellcome Sanger Institute, said it is not known if the antioxidant therapy would work in other tissues. It could even have a reverse effect. The study found that antioxidant alone without exposure to radiation did not help normal cells battle the mutant clones.
Murai said:
Giving mice an antioxidant before exposing them to low doses of radiation gave healthy cells the extra boost needed to fight against the mutant cells in the oesophagus and make them disappear. However, we don’t know the effect this therapy would have in other tissues – it could help cancer-capable cells elsewhere become stronger. What we do know is that long term use of antioxidants alone is not effective in preventing cancer in people, according to other studies.
The team says that more research is clearly needed but this study serves to highlight the possibility of developing therapies to prevent cancer.
Murai concluded:
“Medical imaging procedures using radiation, such as CT scans and x-rays, have a very low level of risk – so low that it’s hard to measure. This research is helping us understand more about the effects of low doses of radiation and the risks it may carry. More research is needed to understand the effects in people.
