Low doses of radiation promote cancer prone cells, study suggests

Low doses of radiation – the equivalent to three CT scans – give cancer prone cells a competitive advantage over normal cells in healthy tissues, a study suggests.

Researchers say they have uncovered another potential cancer risk as a result of radiation that needs to be recognised.

They studied the effects of low doses of radiation in the oesophagus of mice, and found that low doses of radiation increase the number of cells with mutations in p53, a well-known genetic change associated with cancer.

But when the mice were given an antioxidant before radiation, it promoted the growth of healthy cells, which outcompeted and replaced the mutant cells.

However, the antioxidant alone without exposure to radiation did not help normal cells battle the mutant clones.

The results, published in Cell Stem Cell, indicate low doses of radiation promote the spread of cancer-capable cells in healthy tissue.

The team from the Wellcome Sanger Institute and the University of Cambridge recommend this risk should be considered when radiation safety is assessed.

They say the study also offers the possibility of developing non-toxic preventative measures to cut the risk of developing cancer by bolstering our healthy cells to outcompete and eradicate cancer-capable cells.

Dr David Fernandez-Antoran, 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.”

The radiation exposure from medical imaging, and other low doses are considered safe as they cause little DNA damage and apparently minimal effect on long-term health.

In this new study, researchers found low doses of radiation weigh the odds in favour of cancer-capable mutant cells in the oesophagus.

They gave mice a 50 milligray dose of radiation, equivalent to three or four CT scans, and as a result, the p53 mutant cells spread and outcompeted healthy cells.

Co-author Dr Kasumi 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.”