Genetic mutations linked with cancer inevitably accumulate with age according to a study showing that many elderly people over 50 have acquired DNA changes associated with leukaemia.
Scientists estimated that more than 20 per cent of people aged between 50 and 60, and 70 per cent of people over 90 have blood cells marked with the same DNA mutations found in leukaemia cells.
“Leukaemia results from the gradual accumulation of DNA mutations in blood stem cells, in a process that can take decades,” said Thomas McKerrell of the Wellcome Trust Sanger Institute near Cambridge, where the work was carried out.
“Over time, the probability of these cells acquiring mutations rises. What surprised us was that we found these mutations in such a large proportion of elderly people,” Dr McKerrell said.
“This study helps us understand how ageing can lead to leukaemia, even though the great majority of people will not live long enough to accumulate all the mutations required to develop the disease,” he said.
Scientists believe that there is a constant repair process going on within the cells of the body, which mends damaged DNA and prevents the onset of cancer development.
However, this process becomes more inefficient as we grow older. The study analysed the blood cells of more than 4,000 people using a sensitive method of sequencing the genetic code at 15 locations in the human genome which were known to be altered during the early development of leukaemia.
“Ultra-deep sequencing has allowed us to see the very beginnings of cancer,” says George Vassiliou, senior author of the study, published in Cell Reports, at the Sanger Institute and Cambridge University Hospitals NHS Trust.
“These mutations will be harmless for the majority of people but for a few unlucky carriers they will take the body on a journey towards leukaemia. We are now beginning to understand the major landmarks on that journey,” Dr Vassiliou said.Reuse content