The 17-Gene Genomic Prostate Score Assay Is Prognostic for Biochemical Failure in Men With Localized Prostate Cancer After Radiation Therapy at a Community Cancer Center

Abstract

Purpose: The objective of this study was to assess the association between the Oncotype DX Genomic Prostate Score (GPS) assay and long-term outcomes in men with localized prostate cancer (PCa) after radiation therapy (RT). We hypothesized that the GPS assay is prognostic for biochemical failure (BCF), along with distant metastasis (DM) and PCa-specific mortality in patients with PCa receiving RT. Methods and Materials: We retrospectively studied men with localized PCa treated with definitive RT at Georgia Urology from 2010 to 2016. The primary objective was to assess the association between GPS results and time to BCF per the Phoenix criteria; we also assessed time to DM and PCa-specific mortality. We used Cox proportional hazards regression models for all analyses, with clinicopathologic covariates determined a priori for multivariable modeling. Results: A total of 450 patients (median age, 65 years; 35% Black) met eligibility criteria. There was a strong univariable association between GPS result and time to BCF (hazard ratio [HR] per 20-unit increase = 3.08; 95% confidence interval [CI], 2.11-4.46; P < .001), which persisted after adjusting for clinicopathologic characteristics in multivariable analyses. We also observed this association for time to DM (HR = 5.19; 95% CI, 3.06-8.77; P < .001) and PCa-specific mortality (HR = 13.07; 95% CI, 4.42-49.39; P < .001). Race was not a predictor of time to BCF or DM, and the GPS assay was strongly prognostic for all endpoints in Black and White patients. Conclusions: In a community-based cohort, the GPS assay was strongly prognostic for time to BCF as well as long-term outcomes in men treated with RT for localized PCa.