MUTATIONAL SIGNATURES

Scientists in the UK have achieved a ‘profound’ and major breakthrough in the fight against cancer that could lead to new treatments and possibly even its prevention.

Despite significant advances, very little is known about what triggers cancer, which kills around half the 325,000 Britons diagnosed with it each year.

But British scientists believe they have unlocked the DNA secrets of 30 of the most common forms of the disease. This will now bring us closer in understanding their causes.

In the biggest analysis yet of its kind, the researchers compared DNA from more than 7,000 cancer patients around the world. The cases included the most common forms, including breast, bowel, lung and prostate, which account for more than half of those diagnosed in Britain.

Cancer is caused by mutations in DNA. These mutations are caused by such things as tobacco in the case of lung or throat cancer, and excess ultraviolet light in the case of skin cancer. Researchers looked for patterns in the genetic code of the tumours made by these mutations.

Analysis of the 7,000 DNA samples revealed 21 patterns that between them were responsible for 30 cancers. Working out which food, drink, habit or other external factor causes them could lead to new ways of preventing the disease.

Knowing more about the genetics of cancer should also speed the search for new treatments – and some existing drugs might also work better in those whose tumours are caused by particular patterns.

Certain patterns in the tumour DNA were expected, such as the one caused by smoking; but others were surprising, including one believed to be caused by a protein that helps us fight infections.

Some of the patterns were only found in one type of cancer, while others, such as the marks left by ageing, were found in many different tumours.

Although further research may reveal more patterns – or ‘mutational signatures’ – the scientists, from the Wellcome Trust Sanger Institute near Cambridge, believe they have found most of them.

Professor Mike Stratton, the lead researcher, said:

… This compendium of mutational signatures and consequent insights into the mutational processes underlying them has profound implications for the understanding of cancer development, with potential applications in disease prevention and treatment.