Scientists have developed a genetic test capable of indicating how long a prostate cancer patient is likely to survive.

Researchers say the procedure shows whether urgent surgery is needed, or whether drug treatment will prevent the spread of the disease, or if it is safe to leave the condition untreated, thus saving thousands from painful, unnecessary therapies each year.

With around 35,000 prostate cancer cases diagnosed in Britain every year, even though the cancers grow slowly without requiring treatment, the disease can prove to be fatal with an annual count of 10,000 deaths.

Currently, biopsies, microscopy and scans are some of the techniques doctors use to figure out which cancers are aggressive and which slow growing. But, most of them produce unreliable results, putting many patients at risk of impotence and incontinence because of unnecessary surgery and radiotherapy.

The test by identifying three genetic mutations in DNA, such as, loss of the PTEN gene and rearrangement of the ERG or ETV1 genes, indicates which men are at increased risk of developing aggressive tumours.

According to Dr. Alison Reid, of the Institute of Cancer Research, patients with none of these genetic alterations showed good prognosis, with 85.5% still alive after 11 years.

However, 6% of those having all three mutations had a shorter life expectancy, with only 13.7% of these patients still alive after 11 years.

Researchers reporting in the British Journal of Cancer said just one DNA mutation could not predict survival.

The most common cancer in men, including the second highest cause of male cancer-related deaths worldwide, prostrate cancer kills around 254,000 men a year.