Washington, DC (UroToday.com): Dr. Daniel Lin gave an overview of currently available genomic biomarkers for risk stratification of localized prostate cancer. He discussed that genomic biomarkers require performance measures for clinical utility. These include improved risk stratification over traditional risk categories (NCCN, AUA, CAPPRA), probability of adverse versus favorable pathology, response to adjuvant radiation, metastatic free survival, or cancer-specific mortality.
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Current markers include Prolaris, Oncotype DX, Decipher, ProMark.
Prolaris is based on prostate biopsy that evaluates for 31 cell cycle progression (CCP) signature genes. The marker has been shown to improve risk stratification as well as be prognostic for prostate cancer specific mortality in those who choose watchful waiting (Cuzick et al, Lancet Oncology 2011). It has also been shown to be predictive of biochemical relapse in a post-radical prostatectomy cohort (Cooperberg, JCO 2013). The role of this test is mainly in improved stratification of disease risk. The test report gives information on “aggressive” nature (more or less) than average AUA low or intermediate risk, distribution percentile compared to others in the AUA risk group, and 10-year prostate cancer mortality risk.
Oncotype Dx also evaluates prostate biopsy for 17 gene Genomic Prostate Score (GPS). and has been shown to be prognostic for adverse pathology (upstaging or upgrading). The role of this test is in pre-therapy decision-making. The rest report gives a GPS score ranging from 0-100 which is then compared to the likelihood of favorable pathology (freedom from Gleason pattern 4 disease).
Promark uses prostate biopsy specimen and evaluates it for proteomic signature with end-point being unfavorable pathology similar to Oncotype Dx test.
Decipher test is a post-prostatectomy assay that uses whole prostate specimen and evaluates it for 22 genes. It has been shown to be prognostic for metastatic free-survival after radical prostatectomy (Ross et al, Prostate Canc Pros Dis 2014) as well as response to adjuvant treatment (Den et al, JCO 2015). Clinically it is utilized in high risk post-prostatectomy patients with a potential role for predicting secondary therapy decision (adjuvant versus salvage radiation).
Dr. Lin then cautions about the implications of these tests and how to interpret these results. Are the results actionable? What is a clinically significant change in likelihood of favorable pathology or incidence of metastasis? Also, is prostate cancer specific mortality appropriate in a low risk prostate cancer patients, such as in the Prolaris test? Long-term studies are needed in active-surveillance patients to determine the need of the genomic tests among this group.
Dr. Lin concludes that currently we have data supporting the biomarkers. The biomarkers add to established models that are based on clinical and pathological data. We, however, still need to determine the impact of the biomarkers whether it leads to change in pre/post therapy decision-making and impacts patient counseling.
Daniel Lin, MD
University of Washington Medical Center
Mohammed Haseebuddin, MD. from the Society of Urologic Oncology Meeting - December 2 - 4, 2015 – Washington, DC.
Fox Chase Cancer Center, Philadelphia, PA.