London - British scientists have achieved a “profound” breakthrough in the fight against cancer that could lead to new treatments and possibly even its prevention.
They have unlocked the DNA secrets of 30 of the most common forms of the disease, bringing us closer to understanding their causes.
Despite significant advances in medicine, remarkably little is known about what triggers cancer, which kills half the 325 000 Britons diagnosed with it each year.
In the biggest analysis of its kind, the researchers compared DNA from more than 7 000 cancer patients around the world.
The cases included the most common cancers, including breast, bowel, lung and prostate, which account for more than half of those diagnosed in Britain.
Cancer is caused by mutations in DNA that gather over the course of a person’s life.
These mutations are caused by such things as tobacco in the case of lung or throat cancer, and excess UV light in the case of skin cancer.
The researchers looked for patterns in the genetic code of the tumours that were made by these mutations.
Analysis of the 7 000 DNA samples revealed 21 patterns that between them were responsible for 30 cancers.
Although some were caused by tobacco, sunlight or ageing, the causes of many are unknown.
Working out which food, drink, habit or other external factor causes such changes in the DNA could lead to new ways of preventing the disease.
For instance, if something we eat is shown to cause mutations, people could be told to avoid it in the same way as they are advised to quit smoking to cut the odds of developing lung cancer and wear sunscreen to protect themselves against skin cancer.
Knowing more about the genetics of cancer should also speed the search for new treatments. Some existing drugs might also work better in those whose tumours are caused by particular patterns.
Certain patterns in the DNA of tumours were expected, such as the one caused by smoking. But others were surprises, including one believed to be caused by a protein that helps us fight infections, according to the research published in the journal Nature.
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.
Every cancer had at least two patterns. But breast cancer had five and liver cancer, six. 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.
Lead researcher Professor Sir Mike Stratton, who was knighted this summer for his work on cancer genetics, 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.”
He said that although he normally avoided making grand claims, he believed the research had brought us closer to understanding cancer.
Researcher Dr Serena Nik-Zainal said: “Through detailed analysis we can start to use the overwhelming amounts of information buried deep in the DNA of cancers to our advantage in terms of understanding how and why cancers arise.
“Our map of the events that cause the majority of cancers in humans is an important step in discovering the processes that cause cancer formation.” Professor Nic Jones, chief scientist at the charity Cancer Research UK, said: “We know that environmental factors like smoking and overexposure to ultra-violet rays can cause faults in DNA which can lead to cancer.
“But for many cancers we don’t know what triggers the faults in our DNA that can lead to cancer mutations.
“The genetic fingerprints identified in this fascinating and important study identify several new processes driving the development of cancer.
“Understanding what’s causing them could be an extremely important way to get to the bottom of how cancer develops in the first place – and this will lead to new ways to prevent and treat the disease.”
The study builds on work on tumour DNA by Professor Stratton, covered in the Mail in 2009, that suggested bespoke treatments could be tailored to patients by identifying genetic mutations.
Britons say cancer is their biggest fear – greater than debt, knife crime, Alzheimer’s or losing a job. - Daily Mail