Scientists have discovered that defective stem cells are the root cause of most cases of bowel cancer - which affects more than 36,500 people in the UK each year, killing around 16,000.
Research has shown that when stem cells are immature they can "ignite" bowel cancer by rapidly multiplying to form tumours.
British and Dutch researchers isolated stem cells in the bowels of mice and deleted a gene from them called APC (adenomatous polyposis coli). The damaged stem cells began to multiply rapidly and form tumours.
Dr Owen Sansom, from Cancer Research UK's Beatson Institute for Cancer Research in Glasgow, said: "When we studied the effect of blocking the APC gene in the 'parents' - or stem cells - the results were striking and the cells started to transform within days.
"It was clear the 'ignition point' for the disease was to be found in the stem cells."
Professor Hans Clevers, from the Hubrecht Institute said that he was "excited" by these findings but wanted to establish whether the stem cells behaved the same way in human cancers as they did in mice.