Molecules in semen diagnose prostate cancer
Researchers may have found a better way to monitor prostate cancer other than the controversial PSA test that can cause confusion and has been the subject of much debate. Scientists have found biomarkers for prostate cancer in semen that they say could be used to improve diagnosis and monitoring of the disease.
According to the National Cancer Institute there were 2,707,821 men living with prostate cancer in the United States in 2011. The disease is the most common form of cancer among men in the Western world.
Accurate diagnosis of prostate cancer can be difficult. PSA testing is not specific for the disease. Elevated levels are possible from inflammation from infection or benign prostatic hyperplasia (BPH). Some medications can elevate a man's PSA level.
Biopsy is invasive and can have side effects that include impotence, infection and bleeding. Unnecessary biopsy is a growing concern that can cause physical and emotional stress.
In 2011, the U.S Preventive Services Task Force released (USPSTF) guidelines advising against PSA testing unless men understand "...there is a very small potential benefit and significant potential harms." The recommendation generated almost immediate controversy.
The USPSTF also identified the need for a better way to diagnose and treat prostate cancer, stating PSA screening "is not the answer".
Studies have shown PSA testing has had no impact on rates of prostate cancer deaths, according to background information from the study authors.
Small molecules in semen can identify prostate cancer
Researchers at the University of Adelaide identified small molecules called microRNAs in seminal fluid that can predict aggressive and non-aggressive types of prostate cancer.
The finding means there may be a way to identify prostate cancers that can be "watched" versus those that require more immediate treatment. It also means there may be a better way to sort elevated PSA levels that are the result of prostate cancer from results that stem from BPH or prostatitis.
University of Adelaide research fellow and lead author Dr Luke Selth explains:
"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.
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."
Selth and his team previously determined microRNAs in the bloodstream can predict prostate cancer relapse in men who had prostate cancer surgery.
The discovery that semen holds important clues to prostate cancer severity or whether a man has prostate cancer is important given high rates of overdiagnosis among men whose cancer is slow-growing and could be left untreated. Identifying microRNA in semen offers a new approach for diagnosing aggressive forms of prostate cancer.