Prostate cancer is one of the most common cancers in men and a major cause of cancer-related deaths. Yet it is tricky to diagnose - the commonly used PSA test can result in over- diagnosis and unnecessary further procedures. Now, new research led by the University of Adelaide in Australia promises to improve the accuracy of prostate cancer diagnosis with the help of biomarkers in seminal fluid.
Writing in the journal Endocrine-Related Cancer, the researchers describe how they analyzed seminal fluid samples from 60 men and found small molecules called microRNAs were "surprisingly accurate" at indicating which men had prostate cancer and how severe it was.
The problem with the current PSA (prostate specific antigen) test for prostate cancer is that, while it is very sensitive, it is not highly specific for prostate cancer. For instance, it might be positive for non-cancerous conditions such as prostatic hyperplasia (BPH) and prostatitis.
This results in many unnecessary biopsies and, perhaps more seriously, in substantial over-diagnosis and over-treatment of slow-growing, non-lethal prostate cancers that are probably best left alone and just monitored under a so-called "watchful waiting" regime.
"Biomarkers that can accurately detect prostate cancer at an early stage and identify aggressive tumors are urgently needed to improve patient care," says lead author Dr. Luke Selth, a Young Investigator of the Prostate Cancer Foundation in the US.
One biomarker could differentiate between higher and lower grade tumors
When they analyzed the seminal fluid samples, the team discovered a number of microRNAs known to be increased in prostate cancer. MicrosRNAs are small non-coding molecules that are important for controlling gene expression.
Unlike a PSA test, which is not highly specific for prostate cancer, microRNAs in seminal fluid samples could differentiate men with low tumors from those with higher grade tumors.
They were surprised to find that some of the microRNAs were more accurate than a PSA test at detecting which of the men had cancer and which did not.
They also found one specific microRNA - called miR-200b - could differentiate men with low tumors from those with higher grade tumors. "This is important," explains Dr. Selth, "because, as a potential prognostic tool, it will help to indicate the urgency and type of treatment required."
In previous work, Dr. Selth and his team showed that microRNAs in the blood can predict which men are likely to experience recurrence after their prostate cancer has been surgically removed.
He says they are "excited by the potential clinical application of microRNAs in a range of body fluids," and he and his colleagues are already planning to validate their results with larger groups of patients.
Meanwhile, Medical News Today recently learned how a commercial epigenetic test for prostate cancer, when done alongside initial biopsy, accurately rules out the existence of cancer up to 88% of the time.