A major breakthrough in the detection, and potentially early treatment, of cancer announced yesterday could see the roots of the disease spotted years to decades before any noticeable symptoms appear. The Pan-Cancer Analysis of Whole Genomes Consortium project involved researchers from 37 countries working in collaboration over a decade.
Yesterday the project published 22 individual scientific papers detailing findings that it is thought will provide the foundation for a generation of new research into combating the disease. Someone is diagnosed with cancer in the UK every two minutes.
The body of research indicates that cancers that develop in usually late adulthood can be detected as early as childhood, when ‘mutational signatures’ in genes can already be present. The study has explored the entire cancer genome over the past ten years and scientists involved now believe they know the majority of the mutational signatures that are the telltale signs cancer is likely to develop years down the line.
It is likely to be 10 to 20 years before screening procedures based on the research are available but in the future a sample of blood, which contains fragments of DNA from cells from across the body, could be analysed for signs of these dangerous mutations. The hope is drugs could be created to kill the kinds of cancer that have a years-long incubation period in their earliest stage.
The study, unprecedented in its breadth, examined 47 million genetic changes across more than 2500 human tumours from patients suffering from 38 separate kinds of cancer. They compared the genomes, DNA, of these tumours with healthy cells from the same patients. Cancer results from DNA errors that can occur when cells grow and then divide. Most of these errors are benign but the study identified a limited number of errors, the driver mutations, that appear to be present in cancerous tumours. Half of the early mutations studies involved the same nine genes, indicating that they are behind the early development of cancer.
The scientists were also able to determine the order in which changes to the genome had occurred based on how many times errors were replicated across dividing cells. They discovered around 20% of the mutations occurred very early on the development of a first tumour. That stage could be years to decades before there is enough evidence to detect cancer using current screening methods.
The Crick Institute’s Clemency Jolly commented:
“What’s extraordinary is how some of the genetic changes appear to have occurred many years before diagnosis, long before any other signs that a cancer may develop, and perhaps even in apparently normal tissue.”
How long before symptoms appear after the first DNA mutations that develop into cancer take place seems to vary between different types of cancer. Types with particularly early mutations include ovarian cancer and two kinds of brain tumour – glioblastoma and medulloblastoma. In the case of the latter two, which are usually not detected until late adulthood, genetic mutations are likely to be present in brain cells from as early as childhood. In the case of ovarian cancer, as well as pancreatic neuroendocrine cancer, genetic warning signs have been found up to appear around a decade before eventual diagnosis.
Dr Peter Van Loo of the Cancer Genomics Laboratory of London’s Francis Crick Institute believes the research could eventually lead to drugs able to detect and destroy the cells carrying early stage genetic errors, essentially curing a cancer before it has even developed into one.
“It’s a bit science fiction at the moment but I can see how we might get there.”