e17587 Background: Progression-free survival (PFS) is widely used as a surrogate endpoint for overall survival (OS) in ovarian cancer, but its validity varies across clinical contexts. To evaluate PFS–OS surrogacy using individual-level agreement in a large real-world cohort and trial-level correlation across randomized studies. Methods: An institutional cohort of 4, 269 patients was analyzed to compare factor-specific hazard ratios (HRs) for PFS and OS and to quantify individual-level surrogacy using censored Kendall’s τ. Trial-level HRs were extracted from phase II/III ovarian cancer trials. Surrogacy was assessed using Spearman correlation, Bland–Altman agreement, and weighted meta-regression, with stratified analyses by disease setting, treatment modality, publication era, maintenance therapy, and HRPFS thresholds. Results: In the institutional cohort, HRPFS and HROS showed near-perfect concordance (R = 0. 98) with minimal bias. Censored Kendall’s τ indicated strong individual-level correlation (τ = 0. 78; p < 0. 001), with 89% concordant event ordering. Across trials, PFS and OS demonstrated moderate correlation (ρ ≈ 0. 62) with small mean bias but wide limits of agreement. Surrogacy was strongest in platinum-resistant disease and first-line cytotoxic chemotherapy, and weaker in platinum-sensitive and targeted therapy settings. Maintenance-therapy trials showed more stable agreement than non-maintenance trials. Temporal analyses revealed the most robust surrogacy in the 2010s, with attenuation in the 2020s as treatment heterogeneity increased. Conclusions: PFS is a practical but context-dependent surrogate for OS in ovarian cancer. Strong individual-level and HR-level concordance supports its use, although trial-level surrogacy varies by disease setting, treatment modality, and therapeutic era. Continued validation is essential as modern treatments reshape post-progression outcomes.
Chung et al. (Thu,) studied this question.