Scientists say they have discovered a new method to find if a patient's prostate cancer is aggressive or dormant.
A study published in the British Journal of Cancer Research revealed that tiny bubbles of fat, called exosomes, passed in urine come directly from the tumour and can help decide if early treatment is necessary.
Exosomes contain ribonucleic acid (RNA) molecules which can help doctors to find which genes are switched on and off in an individual's cancer and thus diagnose whether it is aggressive or dormant.
This ability to differentiate is important because dormant prostate cancers will not spread and can be left untreated.
Invasive treatment for prostate cancer can leave men with long-term side-effects including incontinence and impotence.
Until recently, researchers used levels of proteins like prostate specific antigen produced by cancer cells to try to spot the aggressive tumours, while the new method focuses on RNA analysis.
Dr Jonas Nilsson, lead author based at the VU University Medical Centre in Amsterdam, said: "We hope that this innovative approach to studying prostate cancer will reveal new biomarkers for aggressive tumours."