by
Lauren Dubinsky, Senior Reporter | September 13, 2016
The ‘how’ has largely been
a mystery until now
New research from the Wellcome Trust Sanger Institute may help to explain how ionizing radiation can cause cancer.
It’s known that gamma rays, X-rays, and radioactive particles can damage DNA and lead to cancer, but how it happens or how many tumors are caused by radiation damage has been a mystery. The researchers have uncovered that the DNA damage leaves two molecular fingerprints, known as mutational signatures.
"With the two signatures that we have found, we could use them to identify radiation-associated tumours and ask questions of whether they should be treated differently," Dr. Sam Behjati, clinician researcher at the Sanger Institute and the department of pediatrics at the University of Cambridge, told HCB News.
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Previous studies have found that DNA damage often leaves a mutational signature on the genome of a cancer cell. For this study, the researchers searched for mutational signatures in 12 patients with secondary radiation-associated tumors and compared the results with 319 patients that have not been exposed to radiation.
They found two mutational signatures for radiation damage that were independent of cancer type. They then compared the findings with prostate cancers that had or had not been exposed to radiation and found the same signatures.
One of the signatures is a deletion in which small amounts of DNA bases are cut out. The other signature is called a balance inversion, in which the DNA is cut in two places, the middle piece spins around and then joins together in the opposite direction.
Balance inversions don’t occur naturally in the body. However, high-energy radiation could damage the DNA enough for that to happen.
In order to reduce the amount of cancers that are caused by ionizing radiation, Behjati has a few words of advice:
"Really, this boils down to protection from avoidable radiation exposure — careful consideration of the need for scans that use X-rays, and developing further X-ray machines for imaging and radiation treatment to minimize radiation exposure," he said.
