Certain levels of radiation cause cancer – this is a well-established fact. However, what is less understood is how exactly radiation causes cancer to develop. New research published in the journal Nature Communications on September 12 sought to better understand this, and what they found is quite remarkable.
Researchers from the Wellcome Trust Sanger Institute, a non-profit that researches genetics and genomics in the United Kingdom were able to successfully identify two characteristics in human cancers associated with damage to DNA caused by ionizing radiation.
Using these "fingerprint patterns," the scientists say doctors may be able to identify tumors caused by radiation and possibly treat them accordingly.
"Ionizing radiation, such as gamma rays, X-rays and radioactive particles can cause cancer by damaging DNA," reports Medical Xpress. But researchers don't understand exactly how this happens or how many tumors result from radiation exposure.
Researchers find mutational signatures in cancer cells caused by radiation
Past research has found that damage to human DNA tends to leave behind a "molecular fingerprint" or "mutational signature" that's seen "on the genome of a cancer cell.
Using this information, scientists looked for these mutational signatures in 12 patients with secondary radiation-associated tumors, and compared them with 319 that were not exposed to radiation.
"To find out how radiation could cause cancer, we studied the genomes of cancers caused by radiation in comparison to tumours that arose spontaneously," said Dr. Peter Campbell from the UK-based research institute.
"By comparing the DNA sequences we found two mutational signatures for radiation damage that were independent of cancer type. We then checked the findings with prostate cancers that had or had not been exposed to radiation, and found the same two signatures again," sahd Campbell.
"These mutational signatures help us explain how high-energy radiation damages DNA."
'Showers of radiation chop up the genome causing lots of damage simultaneously'
One of the molecular fingerprints include a "balanced inversion," where the DNA has been cut in two places and is rejoined in opposite orientation, reports Medical Xpress. Balanced inversions don't occur naturally in the human body, but may develop as a result of exposure to high-energy radiation. "Ionising radiation probably causes all types of mutational damage, but here we can see two specific types of damage and get a sense of what is happening to the DNA," explains Dr. Sam Behjati, a clinical researcher at the Sanger institute and the Department of Pediatrics, University of Cambridge.
"Showers of radiation chop up the genome causing lots of damage simultaneously. This seems to overwhelm the DNA repair mechanism in the cell, leading to the DNA damage we see."
The research is the first time scientists have been able to actually identify DNA damage caused by ionizing radiation, said Professor Adrienne Flanagan, a collaborating cancer researcher from University College London and Royal National Orthopedic hospital.
"These mutational signatures could be a diagnosis tool for both individual cases, and for groups of cancers, and could help us find out which cancers are caused by radiation," Flanagan said.
A better understanding of this means doctors can decide if certain cancer tumors should be treated differently, she said.