|Researchers have found RNA molecules that is detecable|
in tissue and urine samples of prostate cancer patients.
Researchers have identified a set of RNA molecules that are detectable in tissue samples and urine of prostate cancer patients but not in normal healthy individuals. The study sets the stage for the development of more sensitive and specific noninvasive tests for prostate cancer than those currently available, which could result in fewer unnecessary prostate biopsies with less treatment-related morbidity, according to a new study in The Journal of Molecular Diagnostics.
According to the American Cancer Society, prostate cancer is the second most common type of cancer in American men (after skin cancer), and the second-leading cause of cancer-related death in men (after lung cancer). In 2014, more than 230,000 new cases of prostate cancer will be diagnosed. One in seven American men will get prostate cancer during his lifetime, and one in 36 will die from it. Since most men with prostate cancer have indolent (nonaggressive) disease for which conservative therapy or surveillance is appropriate, the clinical challenge is not only how to identify those with prostate cancer, but also how to distinguish between those who would benefit from surgical or other aggressive treatment from those who would not.
Prostate cancer is primarily detected and monitored by testing for high concentrations of prostate-specific antigen (PSA) in blood samples. High PSA levels are often followed by a biopsy to confirm the presence of cancer and whether it is slow growing or aggressive. However, only 25% of men with raised PSA levels that have a biopsy actually have prostate cancer, so a better marker is needed.
The researchers believe that they have identified a group of RNA molecules, known as long noncoding RNAs (lncRNAs), that hold the potential for serving as better prognostic markers for prostate cancer. lncRNAs were dismissed until recently by scientists as non-functional noise in the genome. However, they are now thought to regulate normal cellular development and are increasingly reported as contributing to a range of diseases, including cancer.
The study profiled the lncRNAs in three distinct groups: (1) human prostate cancer cell lines and normal prostate epithelial cells; (2) prostate adenocarcinoma tissue samples and matched normal tissue samples; and (3) urine samples from patients with prostate cancer or benign prostate hyperplasia, and normal healthy individuals. In each case, the lncRNAs were elevated in prostate cancer patient samples, but not in patients with benign prostate hyperplasia or normal healthy individuals.
One advantage of lncRNAs is that the molecules can be detected in urine samples, which are more easily available than blood tests. One lncRNA, PCA3, was recently commercialized in a urine test to identify which men suspected of having prostate cancer should undergo repeat prostate biopsy. However, discrepancies exist between PCA3 levels and clinicopathologic features. In the current study, PCA3 was detected in some, but not all of the study samples, suggesting that reliance on a single biomarker may be insufficient for prostate cancer detection, whereas combining additional markers may increase the specificity and sensitivity of the test.