Improved diagnosis and management of one of the most common cancers in men - prostate cancer (lat. Prostate Carcinoma) - could result from research at the University of Adelaide, which has discovered that seminal fluid (semen) contains biomarkers for the disease. Dr Luke Selth, University of Adelaide research fellow and lead author of the study said that the commonly used PSA (prostate specific antigen) test is by itself not ideal to test for cancer. However, study results showed that the presence of certain molecules in seminal fluid indicates not only whether a man has prostate cancer, but also the severity of cancer.

Dr Selth explained while the PSA test is very sensitive, it is not highly specific for prostate cancer. This results in many unnecessary biopsies of non-malignant disease. More problematically, PSA testing has resulted in substantial over-diagnosis and over-treatment of slow growing, non-lethal prostate cancers that could have been safely left alone.

Biomarkers that can accurately detect prostate cancer at an early stage and identify aggressive tumours are urgently needed to improve patient care. Identification of such biomarkers is a major focus of Dr Selth's research. Using samples from 60 men, Dr Selth and colleagues discovered a number of small ribonucleic acid (RNA) molecules called microRNAs in seminal fluid that are known to be increased in prostate tumours. The study showed that some of these microRNAs were surprisingly accurate in detecting cancer.

The presence of these microRNAs enabled to more accurately discriminate between patients who had cancer and those who didn't, compared with a standard PSA test. Researchers also found that the one specific microRNA, miR-200b, could distinguish between men with low grade and higher grade tumours. This is important because, as a potential prognostic tool, it will help to indicate the urgency and type of treatment required.

This research builds on previous work by Dr Selth's team, which demonstrated that microRNAs in the blood can predict men who are likely to relapse after surgical removal of their prostate cancer. Dr Selth emphasized that the scientific team is excited by the potential clinical application of microRNAs in a range of body fluids.