New research which finds that invisible blood in urine may be an early warning sign of bladder cancer is likely to shape guidelines for clinicians.

Scientists at the University of Exeter Medical School found that one in 60 people over the age of 60 who had invisible blood in their urine (identified by their GP testing their urine) transpired to have bladder cancer.

The figure was around half those who had visible blood in their urine – the best known indicator of bladder cancer.

However, it was still higher than figures for other potential symptoms of bladder cancer that warrant further investigation.

Lead author Sarah Price, a PhD student at the University of Exeter Medical School, led the first robust study to investigate whether invisible blood in urine can indicate bladder cancer.

Speaking as the study is published in the British Journal of General Practice on September 1 2014, she said: "It is well known that if you see blood in your urine you should contact your GP, who is likely to refer you for tests. But there is no clear guidance for GPs on what to do if they detect blood that is not visible during routine tests. We are hopeful that our findings will now lead to robust guidance that it warrants further investigation. Early diagnosis is crucial to have the best chance of successfully treating bladder cancer. The three-quarters of patients who are diagnosed early have much better outcomes than those whose disease is diagnosed late. Anything we can do to boost early detection is crucial to help save lives."

The study examined more than 26,000 people whose anonymised data contributed to the Clinical Practice Research Datalink; this is a large research database used by the Exeter team in several cancer studies.

The team found that the risk of bladder cancer was 1.6 per cent in people over 60 who had invisible blood in their urine.

Around 10,000 people in the UK are diagnosed with bladder cancer each year.

The condition is more common in men than women and in older people, with the average age of diagnosis at 68.

Smoking is among the main causes.

Source: University of Exeter