A simple blood test which detects five of the most deadly types of cancer is being developed by scientists.

Researchers at the National Human Genome Research Institute in the US have discovered that when breast, bowel, lung, womb or stomach cancer is present in the body, one particular gene changes its chemical signature.

The scientists think that change occurs when the body starts to lose the fight against the disease.

British charities said it could work like a 'warning klaxon,' sounding the alarm that cancer is present, at a time when treatments are likely to be most effective.