London, Mar 21 (IANS): Researchers from University of East Anglia in the UK have discovered why some prostate cancers are more aggressive, spread to different parts of the body and ultimately cause death.

The findings showed how the number of 'aggressive' cells in a tumour sample defines how quickly the disease will progress and spread.

They also revealed three new subtypes of prostate cancer that could be used to stratify patients for different treatments.

"Prostate cancer usually develops slowly and the majority of cancers will not require treatment in a man's lifetime. However, doctors struggle to predict which tumours will become aggressive, making it hard to decide on treatment for many men," said lead researcher Professor Colin Cooper.

The team studied gene expression levels in 1,785 tumour samples.

They found that the amount of DESNT subtype cells in a sample is linked with the likelihood of disease progression -- the more DESNT cells, the quicker the patient is likely to progress.

"If you have a tumour that is majority DESNT, you are more likely to get metastatic disease, in other words it is more likely to spread to other parts of your body. This is a much better indication of aggressive disease," informed co-lead researcher Dr Daniel Brewer.

"We also identified three more molecular subtypes of prostate cancer that could help doctors decide on different treatment options for patients," he added in a paper published in the British Journal of Cancer.

Prostate cancer is the second most commonly occurring cancer in men and the fourth most commonly occurring cancer overall. There were 1.3 million new cases in 2018, according to the World Cancer Research Fund.

The findings come after the same team developed a test that distinguishes between aggressive and less harmful forms of prostate cancer, helping to avoid sometimes-damaging unnecessary treatment.