NEW genetic clues as to how deadly pancreatic cancer spreads through the body have offered hope of finding better tests and treatments for the disease.
Patients with pancreatic cancer have poor survival rates, with only two to three in every 100 surviving for more than five years after diagnosis.
Now research has discovered why the disease is so difficult to treat, with tumours spreading and their genes changing as they move around the body.
Another study found that the cancer could take 20 years to start spreading and turn deadly, giving scientists the potential to develop new methods of detecting the disease early.
The first study, published in the journal Nature, found that when pancreatic cancer spreads it splits into an extended family of tumour sites that are all related but genetically different. This is one reason why the disease is so difficult to treat.
The British-led research focused on the forces of evolution at work in rapidly mutating pancreatic tumours. Scientists demonstrated that not only does the cancer change between patients, but it also creates genetically different strains at each new tumour site within a single person.
Dr Peter Campbell, from the Wellcome Trust Sanger Institute in Hinxton, Cambridgeshire, said: "We have always known that pancreatic cancer is a particularly aggressive disease. This study illustrates why it is so challenging.
"Each metastasis is its own tumour, each evolving, each striving for dominance, each adapting to life outside the pancreas. When we treat cancer that has spread through the body, we're not just treating one tumour, we might be treating tens of genetically distinct tumours."
The other study published yesterday, which also investigated the genetics of pancreatic cancer, confirmed that the disease starts off slow-growing but is usually only detected at an advanced and deadly stage.
On average, ten years passed before the cancer started to spread and some cases took almost 20 years to become lethal, the research found.
Researcher Dr Bert Vogelstein, from the Howard Hughes Medical Institute in Maryland, US, said: "There have been two competing theories explaining why pancreatic cancers are so lethal.
"The first is that pancreatic tumours are aggressive right from the get-go and spread to other organs very quickly. The second theory is that pancreatic tumours are, in fact, not more aggressive than other tumours, but that symptoms appear so late in the process that patients have little chance of surviving.
"We were surprised and pleased to discover that this second theory is correct, at least for a major fraction of tumours.It means that there is a window of opportunity for early detection."
Dr Laura Bell, science communications officer at Cancer Research UK, said: "This research suggests there is potentially an opportunity to detect pancreatic cancer at an earlier stage.
"Although developing an effective screening test is still some way off, this study adds to our understanding of how we could tackle this disease in future."