Lead author Dr. Luke Selth of the University of Adelaide's Dame Roma Mitchell Cancer Research Laboratories said the commonly used Prostate Specific Antigen test is not an ideal test for prostate cancer because the blood test, while often higher in men with prostate cancer, could also indicate
non-cancerous conditions such prostatitis -- inflammation of the prostate -- and benign prostatic hyperplasia, or enlargement of the prostate.
The PSA test might give false results, both positive and negative. A false positive occurs when a man's PSA level is elevated but no cancer is actually present but might result in prostate biopsy, infection, pain and bleeding. A false negative occurs when a man's PSA level is low, but he has prostate cancer.
"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," Selth said in a statement.
"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."
Selth and colleagues said the study involved 60 men. The researchers discovered several small ribonucleic acid molecules -- microRNAs -- in seminal fluid known to be increased in prostate tumors.
"The presence of these microRNAs enabled us to more accurately discriminate between patients who had cancer and those who didn't, 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."
The findings were published in the journal Endocrine-Related Cancer.