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In a breakthrough in cancer research, scientists have discovered that the cause of cancer is written into the DNA of tumours.

This research, published in the peer-reviewed journal Cell earlier in April 2019, will not only make it possible to pinpoint the exact environmental culprit and the extent to which certain carcinogens contribute to cancer, it may also reveal causes of cancer  unknown before.

Previously, the extent to which factors such as air pollution, pesticides or even cigarette smoke were to blame for the development of cancer has been unknown and the exact roots of cancer have proven to be elusive. For example, scientists have been unable to determine the exact extent to which lung cancer could be attributed to smoking and if the disease might be linked to other factors such as air pollution.

Scientists at Cambridge University and King’s College London exposed human stem cells to a combination of 77 chemical carcinogens and therapeutic agents, two sources of radiation and various controls that damage human DNA.

They were able to develop a catalogue of DNA mutation “fingerprints”, or signatures, caused by 41 environmental agents that are linked to cancer.

“Mutational signatures are the fingerprints that carcinogens leave behind on our DNA, and just like fingerprints, each one is unique,” says Serena Nik-Zainal, one of the authors of the study from the department of medical genetics at Cambridge University.

Through researching the DNA of the tumour, scientists will be able to determine what exactly triggered its formation. As David Phillips of King’s College London explains, “It should allow us to examine a patient’s tumour and identify some of the carcinogens they have been exposed to that may have caused the cancer.”

The UN reported in 2018 that, worldwide, one in five men and one in six women will develop cancer in their lifetime while one in eight men and one in eleven women will die from it.