Genetic Tests Improve Prognostication for Newly Diagnosed Patients with Prostate Cancer
Key findings
- Several genetic tests are now commercially available to improve risk stratification of patients with prostate cancer
- This systematic review reports on 21 studies: eight of Prolaris, eight of Oncotype Dx Prostate and five of Decipher
- The tests provide information about the risk of adverse pathology, biochemical recurrence, metastasis and disease-specific mortality, including among newly diagnosed patients
- The tests can be used alone, but several models have been developed to improve their performance by combining them with clinical variables
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Several genetic tests of biopsy specimens are now commercially available to improve risk stratification of patients with prostate cancer (PCa). Noam David Fine, MD, a resident in the Harvard Urologic Surgery Residency Program at Massachusetts General Hospital, and colleagues recently systematically reviewed the literature on these tests, including evidence about their use in newly diagnosed patients. Their work is published in BJUI International.
Analyzed Studies
The researchers identified 21 studies published between 2012 and 2018. Eight concerned the Prolaris test, eight concerned the Oncotype Dx Prostate test and five concerned the Decipher test.
Prolaris
The Prolaris test evaluates the expression of 31 cell-cycle–related genes and 15 housekeeping genes. The results are represented as a cell-cycle progression (CCP) score. The research indicated:
- Risk of death: Two studies confirmed the prognostic value of Prolaris for PCa–specific mortality. In one of them the CCP score was a stronger predictor of mortality when combined with the Cancer of the Prostate Risk Assessment (CAPRA) score
- Risk of recurrence and metastasis: One study showed that the CCP score predicted the 10-year risk of biochemical recurrence (BCR) or metastasis after radical prostatectomy (RP). In another, CCP predicted BCR in men treated with external-beam radiation therapy, either alone or in combination with androgen deprivation therapy
- Management: Three studies showed that Prolaris affects how physicians decide to treat PCa (intervention vs. non-intervention)
- Cost-effectiveness: An Ontario budget impact analysis evaluated the utility of Prolaris for National Comprehensive Cancer Network (NCCN) low- or intermediate-risk localized PCa. The projected savings from increased use of active surveillance and decreased use of interventional treatments did not offset the high cost of Prolaris
Oncotype Dx Prostate
The Oncotype Dx test evaluates the expression of 12 cancer-related genes and five housekeeping genes. The results are represented as a Genomic Prostate Score (GPS). The research indicated:
- Adverse pathology: Four studies confirmed that GPS predicts adverse pathology at the time of RP: two validation studies, a meta-analysis of those two studies and a study that determined the threshold value. In the meta-analysis, the performance of the GPS was even better when added to CAPRA, NCCN risk group or American Urological Association risk group
- Risk of recurrence and metastasis: One study reported that GPS significantly predicted BCR-free survival and metastasis-free survival
- Management: Three studies found that GPS influenced affected treatment methods and/or treatment options within each method. In one of these studies, knowledge of GPS improved patients' acceptance of treatment recommendations
- Cost-effectiveness of Oncotype Dx for very-low-, low- and favorable intermediate-risk patients was assessed by an insurance company in upstate New York. The results showed savings of $2,286 per patient because of increased surveillance and decreased interventions
Decipher
The Decipher test evaluates 22 cancer-related genes. The results are represented as a Genomic Classifier score intended to help predict the risk of metastasis after RP. The research indicated:
- Concordance between biopsy and RP: Two studies reported a correlation between Decipher scores obtained from biopsy and RP specimens
- Risk of recurrence and metastasis: Three studies showed that Decipher predicted BCR and/or metastasis post-RP. Prediction of metastasis was improved when Decipher was combined with NCCN risk group
Opportunities to Improve Care
Genetic tests that aid risk stratification have the potential to reduce both over- and undertreatment of PCa. Their cost-effectiveness cannot be determined until more is known about how they influence clinical decision-making and long-term patient outcomes. For now, none of the major guidelines on PCa management provides definitive recommendations for incorporating these tests into practice.
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