The findings, reported by the Wellcome Trust Sanger Institute in the journal in Cell Reports, suggests "it is almost inevitable" that most people will develop genetic mutations associated with the blood cancer if they live long enough, the researchers said.. Although most mutations are harmless, they do provide new insights into the origins of cancer, they added.
 

The researchers, who studied 4,219 people without any evidence of blood cancer, found that up to 20 percent of those aged 50-60 and more than 70 percent of those over 90 had blood cells with the same gene changes found in leukemia.
 

The study used an extremely sensitive test to detect DNA mutations in as few as 1.6 percent of blood cells and analyzed 15 locations in the human genome known to be altered in leukemia.
 

The results suggest the incidence of precancerous cells in the general population is much higher than previously thought and increases dramatically with age.
 

"Leukemia results from the gradual accumulation of DNA mutations in blood stem cells, in a process that can take decades," said Thomas McKerrell, M.D., who helped lead the study.
 

"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. This study helps us understand how aging can lead to leukemia, even though the great majority of people will not live long enough to accumulate all the mutations required to develop the disease."
 

George Vassiliou, MD., a researcher with the Sanger Institute and Cambridge University Hospitals NHS Trust, noted the gene mutations uncovered by the study are not life-threatening to most people who have them. But the findings offer new insights into the origins of cancer and the way advancing age increases risk.
 

"Ultra-deep sequencing has allowed us to see the very beginnings of cancer," he said. "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 leukemia. We are now beginning to understand the major landmarks on that journey."