UK scientists say they are closer to developing a pill that could protect people against bowel cancer.
Experts hope the findings will ultimately lead to a pill for humans
The experimental drug AZD2171 appears to stop bowel wall growths, called polyps, from turning cancerous by starving them of blood.
If the findings in mice can be replicated in humans, it could provide another weapon against what is the second biggest cause of cancer death.
The Cancer Research UK study appears in the journal Carcinogenesis.
Currently doctors can help prevent the development of bowel cancer by removing the polyps before they become malignant.
However, only people with a higher than average risk of developing the disease are specifically screened for these polyps.
A national bowel cancer screening programme is now being rolled out for everybody aged between 60 and 69 years, who will be offered checks every other year.
Bowel cancer is one of the most common cancers - around 35,000 people in the UK are diagnosed with the disease each year.
Polyps are fairly common and it is estimated that around 40% of people over the age of 50 have them.
However, only between 5 and 10% of these polyps will go on to develop into cancer. And when bowel cancer is found early, around nine out of 10 people can be cured.
For polyps to grow and become cancerous, they need to grow their own blood vessels.
The drug AZD2171 interferes with a molecule called vascular endothelial growth factor (VEGF), which acts as the signal telling cells to grow new blood vessels.
BOWEL CANCER SYMPTOMS
A persistent change in bowel habit to looser or more frequent bowel motions
Tummy pain, especially if severe
A lump in your tummy
If these symptoms last longer than four to six weeks, visit your doctor
By disrupting the VEGF signalling, the drug can stop blood vessel formation and therefore restrict tumour growth.
Dr Robert Goodlad, who led the study at Cancer Research UK's London Research Institute, said: "This initial work in mice may one day translate to man and could provide the basis for a pill to treat polyps and so prevent tumours.
"We have shown for the first time that it is possible to treat mice using a drug that targets this specific pathway.
"Early clinical trials of this drug in humans with advanced bowel cancer have found that it is well tolerated without serious side effects.
"Larger scale studies now have to be undertaken to see if the drug is effective."
Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "These are very promising early findings and we look forward to seeing how the drug performs in patients."