By Fiona Macrae
Last updated at 12:23 AM on 7th January 2011
The mystery of ‘instant cancers’ - tumours that seem to appear out of nowhere - has been solved by British scientists.
In some cases, a single apocalyptic ‘explosion’ in a cell can cause as much damage to the DNA as decades of hard living.
The finding, from the Wellcome Trust Sanger Institute near Cambridge, contradicts the long-held theory that cancer is the consequence of hundreds, or thousands, of mutations that build up over a person’s lifetime.
It suggests that no matter how healthy some people try to be, fates is conspiring against them. And it helps explain why some people are diagnosed with cancer only months after x-rays or other tests found no trace of the disease.
The discovery was made from the study of the genetic flaws in 750 tumours.
In most cases, the damage seen to the chromosomes fitted with the conventional picture of cancer creeping up over many years.
But at least one tumour in 40 didn’t fit the standard pattern, the journal Cell reports.
Instead, the damage appeared to have been done almost overnight.
Researcher Dr Peter Campbell said: ‘The results astounded us. It seems that in a single cell, in a single event, one or more of the chromosomes explode - literally into hundreds of fragments.’
If the cell then botches the repair, stitching the fragments back together in a ‘higgledy piggledy’ fashion, the damage to its genome, or cache of DNA, leaves it ripe for the rapid development of cancer.
Dr Campbell said: ‘The cell should say “that’s it”, and give up, but instead it tried to piece the chromosomes back together like a valuable piece of porcelain.
‘They attempt to reconstruct the unreconstructable and they wind up with a disastrous genome that shortens the road to cancer.’
The phenomenon is particularly common in bone cancers, where the distinct pattern of damage is seen in up to one in four cases. But it thought to be to blame for more than one in 40 of all cases of the disease.
Dr Campbell said: ‘Many cancers will take years, decades, to develop. But we also know that in some patients cancers seem to appear much more quickly than that.
'We have examples of people who had a totally normal mammogram or other x-ray and within a few months they develop a nasty aggressive cancer and it may be that a single catastrophic event shortened the development.’
The researchers aren’t sure what triggers such the catastrophic damage behind ‘instant cancers’ but possible culprits include x-rays and sunburn.
Dr Campbell said: ‘If we can understand its roots, we may learn how to prevent that kind of cancer happening.’
The study is part of a landmark project to chart the genetic flaws in dozens of types of cancer.
In future, every patient could have their own ‘mutation chart’, mapping the precise flaws behind their illness and indicating the best drugs to treat them.
Read more: http://www.dailymail.co.uk/health/article-1344740/Why-cancers-develop-instant–cells-explode-wreaking-havoc-DNA.html#ixzz1AsUCCSuP
