Data support PCa markers, but more study needed

Washington-The last several years have witnessed an increasing amount of information and research on the genetic makeup of prostate cancer. Along with this deeper understanding of the disease, a litany of new genetic and molecular tests are being presented to urologists treating prostate cancer patients. Sorting out the appropriate use and interpretation of these tests can be challenging. 

Daniel Lin, MD, of the University of Washington, Seattle, spoke at the recent 2015 Society of Urologic Oncology annual meeting on some ways that urologists can use these molecular tests and described data supporting four specific tests.

Dr. Lin explained that these tests are tissue-based platforms and are currently included in some, but not all, clinical practice guidelines. (In February 2016-after Dr. Lin made his presentation-the National Comprehensive Network issued new guidelines on prostate cancer that include several tissue-based tests, including the four mentioned in this article.) He pointed out that many of these tests are used as biomarkers that help answer questions like, “Can we risk stratify within a current risk group to better define some of these populations?” He briefly presented data behind four currently available molecular tests, although he cautioned that the breadth of science and research behind these tests cannot be explained thoroughly in a single presentation.

Also by Dr. Manley: A new castration-resistant prostate cancer entity?

Dr. Lin described the use and interpretation of Prolaris (Myriad Genetics) and how this test likely has the most published data to support its use. Like many of the other tests, it gives clinicians a readout that compares the individual patient to other similar patients according to several clinical and oncologic features. This test is performed on biopsy tissue and uses a signature primarily derived from 31 genes involved in cell cycle progression to give information about prostate cancer-specific mortality for those without treatment along with a more detailed risk stratification.

Next: Oncotype DX, ProMark discussed

Dr. Lin also discussed Oncotype DX (Genomic Health, Inc.), which is also performed on biopsy tissue and uses a signature from 17 genes involved in multiple cellular pathways to give an assessment of the risk of adverse pathology (ie, upgrading or upstaging) on prostatectomy specimens.

Read: How the economy predicts PCa diagnosis, management

The last test in this arena he discussed was ProMark (Metamark Genetics, Inc.), which also uses biopsy tissue but is unique in that it uses the expression levels of eight proteins to generate a signature that is predictive of unfavorable pathology at time of surgery.

Unlike the first three tests, which are used for pre-therapy decision-making, the Decipher Prostate Cancer Classifier (GenomeDx Biosciences Inc.) is a test used after prostatectomy. The test is indicated for patients with “high-risk disease” and involves RNA sequencing for 22 genes on tissue from prostatectomy. These results can be used in predicting the risk of future metastasis and the patient’s response to adjuvant radiation.

“None of these tests have been evaluated in cohorts of active surveillance patients,” cautions Dr. Lin.  He does go on to acknowledge that it is likely some physicians are currently using these test in the management of their active surveillance patients but again highlights the current lack of data in this population.  In closing, he said, “There is clearly data to support these biomarkers,” but stressed the need to continue to evaluate the clinical utility of these tests over commonly used clinical models.

Also see: Utility of PCa markers in African-Americans differs

Adam Kibel, MD, of Brigham and Women’s Hospital, Boston, served as session chair during Dr. Lin’s presenation.

“We need better tools to risk stratify our patients, and these tests deliver,” Dr. Kibel said.

Look for an exclusive interview with Dr. Lin on the subject of prostate cancer biomarkers and tests in an upcoming issue of Urology Times.

Click here for more articles on prostate cancer.

To get weekly news from the leading news source for urologists, subscribe to the Urology Times eNews.