Genomic Prostate Score (GPS) as a Prognostic Biomarker in Patients With Localized Prostate Cancer Undergoing Focal Therapy

ABSTRACT Background Focal therapy (FT) encompasses ablation of the prostate cancer (PCa) while preserving the surrounding benign tissue, aiming to minimize or spare patients from postoperative complications. Although FT has been proven effective, the multifocal and heterogeneous nature of PCa is a significant concern regarding the risk of disease progression. The Genomic Prostate Score (GPS) has been shown to aid in the risk stratification of patients with localized disease; however, its role in patients undergoing FT remains unclear. We evaluated the association between the GPS performed on pretreatment biopsy cores and the oncological outcomes of patients with localized PCa treated with FT at our institution. Methods This is an institutional review board‐approved retrospective review of a prospectively maintained database of PCa patients undergoing prostate FT at Duke between 2005 and 2020. The study included men with localized PCa, preoperative diagnostic prostate biopsy tissue availability, and a minimum follow‐up of 1‐year. The primary outcome was to evaluate the association between the GPS assay performed on the preoperative prostate biopsy tissue with cumulative incidence of treatment‐failure (TF) defined as requirement of salvage therapy and/or development of metastasis, and prostate cancer‐specific death and failure‐free survival (FFS). The secondary outcome was to assess whether the GPS assay could predict ≥ Gleason Grade Group (GGG) 2 biopsy recurrence/persistence following ablation. Results A total of 81 patients met the inclusion criteria. The median follow‐up was 48 months (IQR, 35–98). The median age, preoperative PSA, and PSA density were 74 years (IQR, 68–77), 7.4 ng/ml (IQR, 5.5–10), and 0.19 ng/mL/mL (0.14–0.22), respectively. Of 81 patients, 55 (68%) and 7 (9%) had intermediate and high‐risk disease. The median GPS score was 30 (IQR, 24–40), and 21/81 (26%) had a GPS result > 40. TF and ≥ GGG2 biopsy recurrence were observed in 15/81 (19%) and 10/81 (12%), respectively. GPS was > 40 in 8/15 (53%) and 7/10 (70%) of patients with TF and biopsy recurrence, respectively. On univariable analysis, GPS was significantly associated with TF (HR 1.07, 95% CI, 1.02–1.12, p < 0.01) and biopsy recurrence/persistence (HR 1.09, 95% CI, 1.03–1.15, p = 0.08). Men with GPS of 40–100 were found to be significantly at higher risk of having TF (HR 4.19, 95% CI, 1.26–13.89, p = 0.01) and in‐field biopsy recurrence (HR 14.3, 95% CI, 2.48–82.83, p = 0.003). Conclusion Among men treated with focal ablation for localized PCa, the GPS assay appears to be a prognostic indicator of FFS and GGG ≥ 2 biopsy recurrence. Further studies with large sample sizes are required to validate these findings.