Timing of biomarker testing and associated clinical outcomes in ovarian cancer patients: A retrospective study.

Abstract

e17574 Background: In ovarian cancer (OC) patients, biomarker testing can inform treatment decisions and thereby guide optimal management. The timing of testing for biomarkers such as BRCA , homologous recombination deficiency (HRD), and folate receptor α (FRα) is not currently standardized in clinical practice. We aimed to characterize biomarker testing rates and the impact of timing of testing on clinical outcomes in OC patients. Methods: This retrospective study utilized the US-based electronic health record-derived deidentified Flatiron Health Research Database to identify adult patients diagnosed with OC from Nov 2022 to Sep 2025 who had biomarker records available at the time of or post OC diagnosis. FRα immunohistochemistry (IHC), BRCA , and HRD testing rates were examined. Among patients who received ≥1 biomarker test and ≥1 line of therapy (LOT), we evaluated the impact of timing of biomarker testing post-diagnosis (0-3, 3-6, ≥6 mo) on first-line progression free survival (PFS) and overall survival (OS) using Cox proportional hazard models with inverse probability weights adjusted for patient demographic and clinical characteristics. A sensitivity analysis was conducted in patients with ≥2 LOT. Results: Of 1685 patients identified, testing rates were 92.3% for BRCA , 59.9% for HRD, and 43.8% for FRα IHC; the FRα IHC retesting rate was 7.9%. FRα testing rates increased in 2023–2025. Among 1029 patients (0-3 mo: n=782; 3-6 mo: n=151; ≥6 mo: n=96) with ≥1 biomarker test and ≥1 LOT, the adjusted hazard ratios (aHRs) for OS (95% CI) were 1.60 (1.08–2.39) and 1.46 (0.90–2.35) in patients tested at 3-6 and ≥6 mo, respectively, compared to patients tested 0-3 mo post-diagnosis, representing a 32-38% risk reduction of death in the 0-3 mo group. The PFS (95% CI) aHRs were 1.15 (0.85–1.55) and 1.45 (1.06–1.97) in patients tested 3-6 and ≥6 mo, respectively, vs patients tested 0-3 mo post-diagnosis. Among 504 patients (0-3 mo: n=233; 3-6 mo: n=113; ≥6 mo: n=158) with ≥1 FRα IHC test and ≥1 LOT, the OS (95% CI) aHRs were 2.14 (1.20–3.80) and 2.03 (1.20–3.41), representing a 51-53% lower risk of death in the 0-3 mo group; plus, PFS (95% CI) aHRs were 1.76 (1.20–2.58) and 2.59 (1.88–3.55) in patients tested at 3-6 and ≥6 mo, respectively, vs patients tested 0-3 mo post-diagnosis. Sensitivity analyses conducted in patients with ≥2 LOT showed consistent results. Conclusions: Testing OC patients early for BRCA , HRD, or FRα was associated with a significant reduction in risk of death and disease progression. The findings suggest that improvement in early biomarker testing has the potential to improve survival outcomes in OC patients.