Exploring the Association Between Homologous Recombination Status, Kelim, and Resectability in High Grade Serous Ovarian Cancer

OBJECTIVES We aimed to evaluate the predictive value of KELIM for achieving complete cytoreduction (R0; no macroscopic residual disease) in patients with high-grade serous ovarian carcinoma and to determine whether its performance and optimal thresholds vary according to homologous recombination status. METHODS This single-center retrospective study included patients with high grade serous ovarian carcinoma treated with neoadjuvant chemotherapy between January 2010 and December 2025. KELIM was calculated for each patient and categorized as favorable (≥1) or unfavorable (<1). Associations with surgical residual disease (R0; no macroscopic residual disease), R1; residual tumor <1 cm, R2; residual tumor ≥1 cm) were assessed. Receiver operating characteristic (ROC) curves determined optimal KELIM cutoffs. We evaluated the association of KELIM and homologous recombination status with progression-free survival; survival outcomes were analyzed using Kaplan–Meier estimates and Cox proportional hazards models. Subgroup analyses were performed according to homologous recombination status. RESULTS Overall, 145 patients were included. Median age was 64 years (interquartile range (IQR) 57–73), and median KELIM was 0.93 (IQR 0.91–1.02). Patients with favorable KELIM (n=58) had significantly higher R0 rates compared to those with unfavorable KELIM (n=87) (77.6% vs 47.1%, p=.002). ROC analysis demonstrated moderate predictive performance for R0 (area under the curve (AUC) 0.668; optimal cutoff 0.995). Optimal KELIM thresholds varied by molecular subgroup, with lower cutoffs in homologous recombination deficient tumors (0.74) and BRCA-mutated (0.745) tumors and higher in homologous recombination proficient tumors (0.94). Favorable KELIM was not significantly associated with progression-free survival (HR 0.78, 95% CI 0.54–1.13, p=0.20). Median progression-free survival was numerically longer among patients with favorable KELIM compared with unfavorable KELIM (16.6 vs 13.7 months), although this difference was not statistically significant. CONCLUSION KELIM was associated with complete cytoreduction in patients with high grade serous ovarian carcinoma, with differences observed according to homologous recombination status. These findings highlight the need for further investigation of KELIM thresholds across distinct molecular subtypes to determine whether subtype-specific approaches may improve its clinical applicability.