Improved diagnosis and management of prostate cancer could result from research that has discovered that seminal fluid (semen) contains biomarkers for the disease. The presence of certain molecules in seminal fluid has been found to indicate not only whether a man has prostate cancer, but also the severity of the cancer.

The commonly used PSA (prostate specific antigen) test is by itself not ideal to test for the cancer, said lead author Luke Selth, PhD, of the University of Adelaide in Australia.

“While the PSA test is very sensitive, it is not highly specific for prostate cancer,” Selth said. “This results in many unnecessary biopsies of nonmalignant disease. More problematically, PSA testing has resulted in substantial over-diagnosis and over-treatment of slow growing, nonlethal prostate cancers that could have been safely left alone.

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“Biomarkers that can accurately detect prostate cancer at an early stage and identify aggressive tumors are urgently needed to improve patient care. Identification of such biomarkers is a major focus of our research,” he said. The study was published in Endocrine-Related Cancer (2014; doi:10.1530/ERC-14-0234).

Using samples from 60 men, 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 tumors. The study showed that some of these microRNAs were surprisingly accurate in detecting cancer.

“The presence of these microRNAs enabled us to more accurately discriminate between patients who had cancer and those who [did not], compared with a standard PSA test,” Selth said. “We also found that the one specific microRNA, miR-200b, could distinguish between men with low grade and higher grade tumors. This is important because, as a potential prognostic tool, it will help to indicate the urgency and type of treatment required.”

In previous work, Selth’s team demonstrated that microRNAs in the blood can predict which men are likely to experience a relapse after surgical removal of their prostate cancer. “We are excited by the potential clinical application of microRNAs in a range of body fluids,” he said.

The research team is now expanding on these studies using larger patient groups to validate their findings.