In the ENACT study, reported in the Journal of Clinical Oncology, Murphy et al found that use of the 12-gene Genomic Prostate Score (GPS) in a predominantly Black patient population with relatively low-risk prostate cancer tended to be associated with reduced selection of active surveillance—primarily among men with lower health literacy.
Study Details
The trial included 200 men from three hospitals in Chicago with National Comprehensive Cancer Network® (NCCN) very low–risk to low-intermediate–risk prostate cancer. They were randomly assigned at diagnosis to standard counseling with (n = 104) or without (n = 96) the 12-gene GPS assay. Overall, 70% were Black, 16% had a college degree, 46% were classified as having low health literacy, and 12% had private insurance. The primary endpoint was treatment choice at a second postdiagnosis visit, with the proportions of patients choosing active surveillance being compared between the two groups.
In contrast to other studies, the net effect of the GPS was to move patients away from active surveillance, primarily among men with low health literacy. These findings have implications for our understanding of how prognostic molecular assays that generate probabilities of poor outcome can affect treatment decisions in diverse clinical populations.— Murphy et al
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Key Findings
On intention-to-treat analysis, active surveillance was selected by 77% of the GPS group vs 88% of the control group (P = .067). In analysis excluding 10 patients in the GPS group who did not receive GPS results due to inadequate specimens, the proportions selecting active surveillance were 74% vs 88% (P = .029).
A shift in NCCN risk following GPS testing occurred in 60% of men in the GPS group. A total of 38 men moved to a higher NCCN risk group; among these, 15 (39%) chose treatment vs active surveillance. Of 15 who moved to a lower risk level, 2 (13%) chose treatment. Among 26 who were initially classified as low-intermediate risk, 18 (69%) moved to unfavorable-intermediate or high-risk, with 14 (54%) choosing treatment.
In subgroup analysis, no significant difference in treatment effect based on race was observed. The sole variable that significantly altered the effect of the GPS intervention was health literacy; compared with the control group, odds ratios (ORs) for choosing active surveillance were 0.16 (95% confidence interval [CI] = 0.04–0.63) among men in the GPS group with below-median health literacy and 1.12 (95% CI = 0.40–3.19) among those with above-median health literacy (P for interaction = .022).
On multivariate analysis, factors significantly associated with choosing active surveillance included:
- NCCN low-risk (OR = 0.23, 95% CI = 0.05–0.96) or low-intermediate–risk (OR = 0.03, 95% CI = 0.01–0.12) vs very low-risk
- Family history of prostate cancer (OR = 4.13, 95% CI = 1.06–16.06)
- Having insurance (Medicare, Medicaid, or private insurance; OR = 3.16, 95% CI = 1.00–9.92) vs no insurance.
The investigators concluded, “In contrast to other studies, the net effect of the GPS was to move patients away from active surveillance, primarily among men with low health literacy. These findings have implications for our understanding of how prognostic molecular assays that generate probabilities of poor outcome can affect treatment decisions in diverse clinical populations.”
Peter H. Gann, MD, ScD, of the Department of Pathology, University of Illinois at Chicago, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the Department of Defense Prostate Cancer Research Program and Genomic Health, Inc. For full disclosures of the study authors, visit ascopubs.org.
