Just Three CT Scans Can Give Cancer-Capable Cells an Advantage

New research is revealing that even low doses of radiation increase the number of cells with mutations in p53, a genetic change associated with cancer.
Loukia Papadopoulos

Just three CT scans can give cancer-capable cells an advantage over normal cells in healthy tissue, finds worrisome new research. Scientists at the Wellcome Sanger Institute and the University of Cambridge studied the effects of a 50 milligram dose of radiation, equivalent to three or four CT scans, in the esophagus of mice and found that it increased the number of cells with mutations in p53, a genetic change associated with cancer.


Replacing p53 mutant cells

Luckily there was a good side to the findings. The researchers experimented with giving the mice an over-the-counter antioxidant, N-Acetyl Cysteine (NAC), before exposure.

They discovered that the antioxidant made normal cells capable of outcompeting and eradicating the p53 mutant cells. Still, that is not enough to stop long term damage, argue the researchers.

"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 esophagus 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," said Dr Kasumi Murai, an author from the Wellcome Sanger Institute.  

So far, low doses of radiation, such as the exposure from medical imaging, have been considered safe but that is because their effects have remained hidden. This new study reveals that even so-called safe low doses of radiation weigh the odds in favor of cancer-capable mutant cells in the esophagus.

 "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 favor of cancer-capable mutant cells. We've uncovered an additional potential cancer risk as a result of radiation that needs to be recognized," said Dr David Fernandez-Antoran, first author from the Wellcome Sanger Institute.

More research needed

The research further outlined the need for more studies on so-called safe levels of radiation exposure.

"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," said Professor Phil Jones, lead author from the Wellcome Sanger Institute and MRC Cancer Unit, University of Cambridge.

The research also points to the possibility of developing new therapies to prevent cancer that consist of boosting healthy cells so that they can naturally push out cancer-capable cells, without any toxic side effects for the patient.

The study is published in Cell Stem Cell.

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