Cause of cancer in DNA of tumours

The cause of cancer is written into the DNA of tumours, scientists have discovered, in a breakthrough that could finally show how much disease is attributable to factors such as air pollution or pesticides.

Until now the roots of many cancers have proved elusive, with doctors unable to tease out the impact of myriad carcinogenic causes that people encounter every day.

In the case of lung cancer, it is not known how much can be attributed to smoking and how much to other factors, such as inhaling pollutants.

Now scientists at Cambridge University and King’s College London have exposed stem cells to dozens of known carcinogens and recorded how each alters its DNA code as cancer forms.

It provides a “fingerprint” or “mutational signature” of the underlying cause and could even show the biggest culprit.

The researchers have released a catalogue of the signatures caused by 41 environmental agents linked to cancer.

“Mutational signatures are the fingerprints that carcinogens leave behind on our DNA, and just like fingerprints, each one is unique,” Dr Serena NikZainal, from Cambridge, said.

“They allow us to treat tumours as a crime scene and, like forensic scientists, allow us to identify the culprit – and their accomplices – responsible for the tumour.”

Around 360,000 people are diagnosed with cancer in Britain each year.

About 38% of cases are thought to be preventable, but the study helps give a better estimation of exactly how deadly environmental factors can be.

The research was published in the journal Cell. –