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Scientists have revealed a 'near-complete' picture of breast cancer for the first time, after publishing results of a project of stunning scale and scope. They have gained this unique insight into the life of the disease after sequencing the entire genomes of 21 breast cancers - and looked at every single fault which helped those tumours develop. The results are published in two papers in the prestigious Cell journal.
Led by researchers from the Wellcome Trust Sanger Institute in Cambridge, and part-funded by Breakthrough Breast Cancer with support from the charity's scientists, the team created a catalogue of all the faults in the genomes of the 21 cancers - three billion letters of DNA - and identified the processes that led to breast cancer.
They found that these faults accumulate in breast cells over many years, initially rather slowly, but picking up more and more momentum as the genetic damage builds up.
They also found an entirely new process, named kataegis, which is involved in the development of cancer, which could play an important role across a range of breast cancers.
Dr Julia Wilson, Head of Research at Breakthrough Breast Cancer, said:
“The size, scale and potential impact of this work is jaw-dropping. It gives us a near-complete picture of breast cancer, showing us how the disease develops from its earliest stages.
“Remarkably, it reveals there may be a tipping point in a breast cancer’s development where it goes from being slow to fast growing.
“This work leaves us in no doubt that breast cancer is a very complex disease, while also supplying us with vital information with which to potentially beat it.”
By the time the breast cancers are large enough to be diagnosed, they are made up of a number of genetically related families of cells, with one such family always dominating the cancer.
Around 50,000 women and 400 men are diagnosed with breast cancer each year in the UK, and around 12,000 die.
The team found different mutational processes act at different times in the lifespan of a breast tumour. Some processes act throughout the evolution of the cancer and some processes only emerge late in its development.
“These findings have implications for our understanding of how breast cancers develop over the decades before diagnosis in adults and might help to find possible targets for improved diagnosis or therapeutic intervention in the future,” says Professor Mike Stratton, lead author and Director of the Wellcome Trust Sanger Institute.
Similar analyses will be undertaken in thousands of cancer genomes, under the International Cancer Genome Consortium, and the team expect many more mutational processes will be defined along the way.